diff --git a/modules/gems/iterables.js b/modules/gems/iterables.js
index 4443f544..b6b55ef2 100644
--- a/modules/gems/iterables.js
+++ b/modules/gems/iterables.js
@@ -41,4 +41,10 @@ export function flatten(arr, result = [], depth, _currLevel) {
   return result;
 }
 
+export function indexArray(array, getKey, getValue = v => v) {
+  let obj = {};
+  array.forEach(item => obj[getKey(item)] = getValue(item))
+  return obj;
+}
+
 export const EMPTY_ARRAY = Object.freeze([]);
diff --git a/modules/ui/bind.js b/modules/ui/bind.js
new file mode 100644
index 00000000..c02bc846
--- /dev/null
+++ b/modules/ui/bind.js
@@ -0,0 +1,41 @@
+import React from 'react';
+import context from 'context';
+
+export default function bind(streamProvider) {
+  return function (Component) {
+    return class Connected extends React.Component {
+      
+      state = {hasError: false, value: null};
+      
+      onChange = value => streamProvider(context.streams, this.props).next(value);
+      
+      componentWillMount() {
+        this.stream = streamProvider(context.streams, this.props);
+        this.detacher = this.stream.attach(value => {
+          this.setState({
+            hasError: false,
+            value
+          });
+        });
+      }
+
+      componentWillUnmount() {
+        this.detacher();
+      }
+      
+      render() {
+        if (this.state.hasError) {
+          return null;
+        }
+        return <Component value={this.state.value}
+                          onChange={this.onChange}
+                          {...this.props} />;
+
+      }
+
+      componentDidCatch() {
+        this.setState({hasError: true});
+      }
+    };
+  }
+}
diff --git a/modules/ui/components/Folder.jsx b/modules/ui/components/Folder.jsx
index 7fbcb922..8dba4e03 100644
--- a/modules/ui/components/Folder.jsx
+++ b/modules/ui/components/Folder.jsx
@@ -2,6 +2,7 @@ import React from 'react';
 
 import ls from './Folder.less'
 import Fa from "./Fa";
+import cx from 'classnames';
 
 export default class Folder extends React.Component{
   
@@ -23,11 +24,11 @@ export default class Folder extends React.Component{
   };
   
   render() {
-    let {title, closable, children} = this.props;
-    return <div className={ls.root}>
+    let {title, closable, className, children} = this.props;
+    return <div className={cx(ls.root, className)}>
       <div className={ls.title} onClick={closable ? this.tweakClose : null}>
         <span className={ls.handle}><Fa fw icon={this.isClosed() ? 'chevron-right' : 'chevron-down'}/></span> 
-        {title}
+        {' '}{title}
       </div>
       {!this.isClosed() && children}
     </div>
diff --git a/modules/ui/components/Row.jsx b/modules/ui/components/Row.jsx
index e69de29b..7ee45324 100644
--- a/modules/ui/components/Row.jsx
+++ b/modules/ui/components/Row.jsx
@@ -0,0 +1,7 @@
+import React from 'react';
+import ls from './Row.less';
+import cx from 'classnames';
+
+export default function Row({className, props, children}) {
+  return <div className={cx(ls.root, className)} {...props} >{children}</div>;
+}
\ No newline at end of file
diff --git a/modules/ui/components/Row.less b/modules/ui/components/Row.less
new file mode 100644
index 00000000..9a2935d5
--- /dev/null
+++ b/modules/ui/components/Row.less
@@ -0,0 +1,9 @@
+.root {
+  line-height: 1px;
+}
+
+.root > * {
+  line-height: 1px;
+  margin: 3px;
+  padding: 5px 3px;
+}
\ No newline at end of file
diff --git a/modules/ui/components/ToolButton.jsx b/modules/ui/components/ToolButton.jsx
new file mode 100644
index 00000000..96fb9461
--- /dev/null
+++ b/modules/ui/components/ToolButton.jsx
@@ -0,0 +1,7 @@
+import React from 'react';
+import ls from './ToolButton.less';
+import cx from 'classnames';
+
+export default function ToolButton({pressed, type, className, ...props}) {
+  return <button tabIndex="-1" className={cx(ls.root, ls[type], pressed && ls.pressed, className)} {...props}/>;
+}
diff --git a/modules/ui/components/ToolButton.less b/modules/ui/components/ToolButton.less
new file mode 100644
index 00000000..8fde30d8
--- /dev/null
+++ b/modules/ui/components/ToolButton.less
@@ -0,0 +1,38 @@
+@import "../styles/theme.less";
+
+.root {
+
+  border: 1px solid @bg-color;
+  margin: 3px;
+  border-radius: 3px;
+
+  padding: 5px 2px;
+  cursor: pointer;
+  background-color: @bg-color;
+
+  outline: none;
+
+  &:hover {
+    background-color: #9c9c9c !important;
+  }     
+  &:active {
+    transition: 200ms;
+    background-color: #BFBFBF !important;
+  }
+  &.pressed {
+    background-color: #7d7d7d;
+  }
+}
+
+.accent {
+  background-color: @color-accent;
+}
+
+.highlight {
+  background-color: @color-highlight;
+}
+
+.danger {
+  background-color: @color-danger;
+}
+
diff --git a/modules/ui/components/controls/Button.less b/modules/ui/components/controls/Button.less
index 8c764b6a..8fab0f2b 100644
--- a/modules/ui/components/controls/Button.less
+++ b/modules/ui/components/controls/Button.less
@@ -17,6 +17,10 @@
   .button-behavior(@color-accent)
 }
 
+.highlihgt {
+  .button-behavior(@color-highlight)
+}
+
 .danger {
   .button-behavior(@color-danger)
 }
diff --git a/modules/ui/components/controls/NumberControl.jsx b/modules/ui/components/controls/NumberControl.jsx
index 4bfede66..e244879f 100644
--- a/modules/ui/components/controls/NumberControl.jsx
+++ b/modules/ui/components/controls/NumberControl.jsx
@@ -8,30 +8,22 @@ export default class NumberControl extends React.Component {
     let {onChange, value} = this.props;
     return <InputControl type='number' 
               onWheel={this.onWheel} 
-              value={ Math.round(value * 1000) / 1000 } 
+              value={ value } 
               onChange={this.onChange}
               inputRef={input => this.input = input} /> 
   }
   
   onChange = e => {
-    let val;
-    try {
-      val = parseFloat(e.target.value)
-    } catch (ignore) {
-      return;
-    }
-    if (!isNaN(val)) {
-      this.props.onChange(val);
-    }
+    this.props.onChange(e.target.value);
   };
   
   onWheel = (e) => {
     let {baseStep, round, min, max, onChange, accelerator} = this.props;
     let delta = e.deltaY;
-    let val = e.target.value;
-    if (!val) val = 0;
     let step = baseStep * (e.shiftKey ? accelerator : 1);
-    val = parseFloat(val) + (delta < 0 ? -step : step);
+    let val = parseFloat(e.target.value);
+    if (isNaN(val)) val = 0;
+    val = val + (delta < 0 ? -step : step);
     if (min !== undefined && val < min) {
       val = min;
     }
diff --git a/modules/ui/styles/common.less b/modules/ui/styles/common.less
new file mode 100644
index 00000000..0809554e
--- /dev/null
+++ b/modules/ui/styles/common.less
@@ -0,0 +1,26 @@
+@import "./theme.less";
+@import "./table.less";
+
+*.autoMarginLeft {
+  margin-left: auto !important;
+}
+
+*.floatRight {
+  float: right;  
+}
+
+.fullWidth {
+  width: 100%;
+}
+
+.dangerColor {
+  color: @color-danger;
+}
+
+.dangerBg {
+  background-color: @color-danger;
+}
+
+.inlineBlock {
+  display: inline-block;
+} 
diff --git a/modules/ui/styles/init/main.less b/modules/ui/styles/init/main.less
index c9b187d9..72fcca75 100644
--- a/modules/ui/styles/init/main.less
+++ b/modules/ui/styles/init/main.less
@@ -1,8 +1,10 @@
 @import "../theme.less";
 @import "../mixins.less";
 
+@fontSize: 11px;
+
 html, pre {
-  font: 11px 'Lucida Grande', sans-serif;
+  font: @fontSize 'Lucida Grande', sans-serif;
 }
 
 body {
@@ -31,3 +33,7 @@ button {
 pre {
   line-height: 1.5;
 }
+
+table {
+  font-size: @fontSize;  
+}
\ No newline at end of file
diff --git a/modules/ui/styles/table.less b/modules/ui/styles/table.less
new file mode 100644
index 00000000..5693501a
--- /dev/null
+++ b/modules/ui/styles/table.less
@@ -0,0 +1,37 @@
+@import "./theme.less";
+
+.stripedTable {
+  & tr:nth-child(even), & th {
+    background-color: @bg-color
+  }
+  & tr:nth-child(odd) {
+    background-color: @bg-color-alt
+  }
+  & tr:hover {
+    background-color: @color-highlight;
+  }
+}
+
+.delineatedTable {
+  border-collapse: collapse;
+  border-spacing: 0;
+  & td, & th {
+    padding: 5px 2px;
+    border: 1px solid @border-color;
+  }
+
+  & tr:first-child th {
+    border-top: 0;
+  }
+  //& tr:last-child td {
+  //  border-bottom: 0;
+  //}
+  & tr td:first-child,
+  & tr th:first-child {
+    border-left: 0;
+  }
+  & tr td:last-child,
+  & tr th:last-child {
+    border-right: 0;
+  }
+}
\ No newline at end of file
diff --git a/modules/ui/styles/theme.less b/modules/ui/styles/theme.less
index 9901d6e8..85e684e2 100644
--- a/modules/ui/styles/theme.less
+++ b/modules/ui/styles/theme.less
@@ -22,6 +22,7 @@
 @color-danger: #b00;
 @color-accent: #2B7D2B;
 @color-neutral: #66727d;
+@color-highlight: #003f5d;
 
 //@work-area-toolbar-bg-color: ;
 //@work-area-toolbar-font-color: ;
diff --git a/web/app/cad/actions/actionDecorators.jsx b/web/app/cad/actions/actionDecorators.jsx
new file mode 100644
index 00000000..e1e00a22
--- /dev/null
+++ b/web/app/cad/actions/actionDecorators.jsx
@@ -0,0 +1,12 @@
+import React, {Fragment} from 'react';
+
+import {mapActionBehavior} from './actionButtonBehavior';
+
+export function actionDecorator(actionId) {
+  let actionBehavior = mapActionBehavior(actionId);
+  return function (Component) {
+    return function ActionDecorator(props) {
+      return <Component {...actionBehavior} {...props}/>;  
+    }
+  }
+}
\ No newline at end of file
diff --git a/web/app/cad/craft/craftPlugin.js b/web/app/cad/craft/craftPlugin.js
index d3b4eb5f..d44aaaa1 100644
--- a/web/app/cad/craft/craftPlugin.js
+++ b/web/app/cad/craft/craftPlugin.js
@@ -2,6 +2,8 @@ import {addModification, stepOverriding} from './craftHistoryUtils';
 import {state, stream} from 'lstream';
 import {MShell} from '../model/mshell';
 import {MDatum} from '../model/mdatum';
+import materializeParams from './materializeParams';
+import CadError from '../../utils/errors';
 
 export function activate({streams, services}) {
 
@@ -54,7 +56,17 @@ export function activate({streams, services}) {
       throw(`unknown operation ${request.type}`);
     }
 
-    return op.run(request.params, services);
+    let params = {};
+    let errors = [];
+    materializeParams(services, request.params, op.schema, params, errors);
+    if (errors.length) {
+      throw new CadError({
+        kind: CadError.KIND.INVALID_PARAMS,
+        userMessage: errors.map(err => `${err.path.join('.')}: ${err.message}`).join('\n')
+      });
+    }
+    
+    return op.run(params, services);
   }
   
   function runOrGetPreRunResults(request) {
@@ -92,6 +104,7 @@ export function activate({streams, services}) {
         streams.craft.models.next(Array.from(models).sort(m => m.id));
       } catch(e) {
         console.error(e);
+        //TODO: need to find a way to propagate the error to the wizard.
         setTimeout(() => streams.craft.modifications.next({
           ...curr,
           pointer: i-1
diff --git a/web/app/cad/craft/intializeBySchema.js b/web/app/cad/craft/intializeBySchema.js
index 8abbc11c..9a5acfe5 100644
--- a/web/app/cad/craft/intializeBySchema.js
+++ b/web/app/cad/craft/intializeBySchema.js
@@ -25,6 +25,8 @@ export default function initializeBySchema(schema, context) {
       val = context.streams.selection[md.type].value[0];
     } else if (md.type === 'object') {
       val = initializeBySchema(md.schema, context);
+    } else if (md.type === 'number') {
+      val = md.defaultValue + '';
     } else {
       val = md.defaultValue;
     }
diff --git a/web/app/cad/craft/validateParams.js b/web/app/cad/craft/materializeParams.js
similarity index 64%
rename from web/app/cad/craft/validateParams.js
rename to web/app/cad/craft/materializeParams.js
index da4fe402..1e081c50 100644
--- a/web/app/cad/craft/validateParams.js
+++ b/web/app/cad/craft/materializeParams.js
@@ -1,8 +1,7 @@
 import {ENTITIES} from '../scene/entites';
 
-export default function validateParams(services, params, schema, errors, parentPath) {
+export default function materializeParams(services, params, schema, result, errors, parentPath) {
 
-  errors = errors || [];
   parentPath = parentPath || ROOT_PATH; 
 
   for (let field of Object.keys(schema)) {
@@ -17,18 +16,20 @@ export default function validateParams(services, params, schema, errors, parentP
       }
     } else {
       if (md.type === 'number') {
-        if (typeof value !== 'number') {
-          errors.push({path: [...parentPath, field], message: 'not a number type'});
-        } else {
-          if (md.min !== undefined ) {
-            if (value < md.min) {
-              errors.push({path: [...parentPath, field], message: 'less than allowed'});
-            }
+        try {
+          value = services.expressions.evaluateExpression(value);  
+        } catch (e) {
+          errors.push({path: [...parentPath, field], message: 'unable to evaluate expression'});
+        }
+        
+        if (md.min !== undefined ) {
+          if (value < md.min) {
+            errors.push({path: [...parentPath, field], message: 'less than allowed'});
           }
-          if (md.max !== undefined ) {
-            if (value > md.max) {
-              errors.push({path: [...parentPath, field], message: 'greater than allowed'});
-            }
+        }
+        if (md.max !== undefined ) {
+          if (value > md.max) {
+            errors.push({path: [...parentPath, field], message: 'greater than allowed'});
           }
         }
       } else if (md.type === 'string') {
@@ -55,12 +56,14 @@ export default function validateParams(services, params, schema, errors, parentP
         if (!Array.isArray(value)) {
           errors.push({path: [...parentPath, field], message: 'not an array type'});
         }
-        value.forEach((item , i) => {
-          validateParams(services, item, md.schema, errors, [...parentPath, i]);
+        value = value.map((item , i) => {
+          let itemResult = {};
+          materializeParams(services, item, md.schema, item, errors, [...parentPath, i]);
+          return itemResult;
         });
       }
+      result[field] = value;
     }
-    return errors;
   }
 }
 
diff --git a/web/app/cad/craft/wizard/components/Wizard.jsx b/web/app/cad/craft/wizard/components/Wizard.jsx
index 9a828cff..40a9b2b6 100644
--- a/web/app/cad/craft/wizard/components/Wizard.jsx
+++ b/web/app/cad/craft/wizard/components/Wizard.jsx
@@ -23,7 +23,6 @@ export default class Wizard extends React.Component {
 
   state = {
     hasError: false,
-    validationErrors: [],
   };
 
 
@@ -51,8 +50,7 @@ export default class Wizard extends React.Component {
 
     let formContext = {
       data: params,
-      validationErrors: this.state.validationErrors,
-      updateParam,
+      updateParam
     };
 
     let Form = operation.form;
@@ -72,15 +70,13 @@ export default class Wizard extends React.Component {
           <Button type='accent' onClick={this.onOK}>OK</Button>
         </ButtonGroup>
         {this.state.hasError && <div className={ls.errorMessage}>
-          performing operation with current parameters leads to an invalid object
-          (self-intersecting / zero-thickness / complete degeneration or unsupported cases)
+          {this.state.algorithmError && <span>
+            performing operation with current parameters leads to an invalid object
+            (self-intersecting / zero-thickness / complete degeneration or unsupported cases)
+          </span>}
           {this.state.code && <div className={ls.errorCode}>{this.state.code}</div>}
           {this.state.userMessage && <div className={ls.userErrorMessage}>{this.state.userMessage}</div>}
         </div>}
-        {this.state.validationErrors.length !== 0 && <div className={ls.errorMessage}>
-          {this.state.validationErrors.map((err, i) => <div key={i}> {err.path.join(' ')} {err.message}</div>)}
-        </div>}
-
       </Stack>
     </Window>;
   }
@@ -110,17 +106,6 @@ export default class Wizard extends React.Component {
 
   onOK = () => {
     try {
-      let {type, params, resolveOperation, validator} = this.props;
-      if (!type) {
-        return null;
-      }
-
-      let operation = resolveOperation(type);
-      let validationErrors = validator(params, operation.schema);
-      if (validationErrors.length !== 0) {
-        this.setState({validationErrors});
-        return;
-      }
       this.props.onOK();
     } catch (error) {
       this.handleError(error);
@@ -135,6 +120,9 @@ export default class Wizard extends React.Component {
     if (error.TYPE === CadError) {
       let {code, userMessage, kind} = error;
       printError = !code;
+      if (CadError.ALGORITMTHM_ERROR_KINDS.includes(kind)) {
+        stateUpdate.algorithmError = true
+      }
       if (code && kind === CadError.KIND.INTERNAL_ERROR) {
         console.warn('Operation Error Code: ' + code);
       }
diff --git a/web/app/cad/craft/wizard/components/Wizard.less b/web/app/cad/craft/wizard/components/Wizard.less
index a16baad4..2d532a39 100644
--- a/web/app/cad/craft/wizard/components/Wizard.less
+++ b/web/app/cad/craft/wizard/components/Wizard.less
@@ -1,15 +1,9 @@
 .errorMessage {
   color: lightgoldenrodyellow;
-}
-
-.userErrorMessage, .errorCode {
-  font-size: 9px;
-}
-
-.userErrorMessage {
-  color: white;
+  white-space: pre-line;
 }
 
 .errorCode {
+  font-size: 9px;
   font-style: italic;
-}
\ No newline at end of file
+}
diff --git a/web/app/cad/craft/wizard/components/WizardManager.jsx b/web/app/cad/craft/wizard/components/WizardManager.jsx
index f6aa720a..43bba870 100644
--- a/web/app/cad/craft/wizard/components/WizardManager.jsx
+++ b/web/app/cad/craft/wizard/components/WizardManager.jsx
@@ -3,17 +3,13 @@ import Wizard from './Wizard';
 import connect from 'ui/connect';
 import decoratorChain from 'ui/decoratorChain';
 import mapContext from 'ui/mapContext';
-import {finishHistoryEditing, stepOverriding} from '../../craftHistoryUtils';
-import validateParams from '../../validateParams';
-import {NOOP} from 'gems/func';
-import {clone} from 'gems/objects';
+import {finishHistoryEditing} from '../../craftHistoryUtils';
 
-function WizardManager({type, changingHistory, resolve, cancel, stepHistory, insertOperation, cancelHistoryEdit, applyWorkingRequest, validator}) {
+function WizardManager({type, changingHistory, resolve, cancel, stepHistory, insertOperation, cancelHistoryEdit, applyWorkingRequest}) {
   if (!type) {
     return null;
   }
   return <Wizard resolveOperation={resolve}
-                 validator={validator}
                  onCancel={changingHistory ? cancelHistoryEdit : cancel}
                  onOK={applyWorkingRequest} />
 }
@@ -22,7 +18,6 @@ export default decoratorChain(
   connect(streams => streams.wizard.effectiveOperation),
   mapContext((ctx, props) => ({
     cancel: ctx.services.wizard.cancel,
-    validator: (params, schema) => validateParams(ctx.services, params, schema), 
     resolve: type => ctx.services.operation.get(type),
     cancelHistoryEdit: () => ctx.streams.craft.modifications.update(modifications => finishHistoryEditing(modifications)),
     applyWorkingRequest: ctx.services.wizard.applyWorkingRequest 
diff --git a/web/app/cad/dom/components/FloatView.jsx b/web/app/cad/dom/components/FloatView.jsx
index c07baf1c..d738e533 100644
--- a/web/app/cad/dom/components/FloatView.jsx
+++ b/web/app/cad/dom/components/FloatView.jsx
@@ -1,11 +1,15 @@
 import React from 'react';
-import ObjectExplorer from '../../craft/ui/ObjectExplorer';
-import OperationHistory from '../../craft/ui/OperationHistory';
 import Folder from 'ui/components/Folder';
-import Fa from '../../../../../modules/ui/components/Fa';
 import ls from './FloatView.less';
-import cx from 'classnames';
+import connect from 'ui/connect';
+import mapContext from 'ui/mapContext';
+import Fa from 'ui/components/Fa';
+import ToolButton from 'ui/components/ToolButton';
 
+@connect(state => state.ui.floatViews.map(views => ({views})))
+@mapContext(ctx => ({
+  getDescriptor: ctx.services.ui.getFloatView
+}))
 export default class FloatView extends React.Component {
 
   state = {
@@ -13,33 +17,32 @@ export default class FloatView extends React.Component {
   };
 
   render() {
+    let {views, getDescriptor} = this.props;
+    
+    function view(id) {
+      let {title, icon, Component} = getDescriptor(id);
+      return <Folder className={ls.folder} title={<span> <Fa fw icon={icon}/> {title}</span>}>
+        <Component/>
+      </Folder>;
+    }
+
+    function icon(id) {
+      let {Icon} = getDescriptor(id);
+      return <Icon />
+    }
+
     return <div className={ls.root}>
       <div className={ls.tabs}>
-        {['project', 'history'].map(tabId => <Tab selected={this.state.selected === tabId} key={tabId}
-                                                  onClick={() => this.setState({selected: this.state.selected === tabId ? null : tabId})}>{getIcon(tabId)}</Tab>)}
+        {views.map(tabId => <ToolButton pressed={this.state.selected === tabId} 
+                                        key={tabId}
+                                        onClick={() => this.setState({selected: this.state.selected === tabId ? null : tabId})}>
+          {<Fa fw icon={getDescriptor(tabId).icon}/>}
+        </ToolButton>)}
       </div>
       
       {this.state.selected && <div className={ls.main}>
-        {this.state.selected === 'project' && <Folder title={<span> <Fa fw icon='cubes'/> Model</span>}>
-          <ObjectExplorer/>
-        </Folder>}
-        {this.state.selected === 'history' && <Folder title={<span> <Fa fw icon='history'/> Modifications</span>}>
-          <OperationHistory/>
-        </Folder>}
-
+        {view(this.state.selected)}
       </div>}
     </div>;
   }
-}
-
-function Tab({children, selected, onClick}) {
-  return <div className={cx(ls.tab, selected && ls.selected)} onClick={onClick}>{children}</div>;
-}
-
-function getIcon(id) {
-  if (id === 'history') {
-    return <Fa fw icon='history'/>;
-  } else if (id === 'project') {
-    return <Fa fw icon='cubes'/>;
-  }
 }
\ No newline at end of file
diff --git a/web/app/cad/dom/components/FloatView.less b/web/app/cad/dom/components/FloatView.less
index 4bd320d4..5cc75788 100644
--- a/web/app/cad/dom/components/FloatView.less
+++ b/web/app/cad/dom/components/FloatView.less
@@ -11,6 +11,11 @@
   font-size: 13px;
 }
 
+.tabs button {
+  display: block;
+  font-size: 13px;
+}
+
 .main {
   display: flex;
   flex-direction: column;
@@ -19,24 +24,8 @@
   overflow-y: scroll;
 }
 
-.tab {
-  
-  border: 1px solid @bg-color;
-  margin: 3px;
-  border-radius: 3px;
-  
-  padding: 5px 2px;
-  cursor: pointer;
-  background-color: @bg-color;
-
-  &:hover {
-    background-color: #9c9c9c !important;
-  }
-  &:active {
-    transition: 200ms;
-    background-color: #BFBFBF !important;
-  }
-  &.selected {
-    background-color: #7d7d7d;
-  }
-}
+.folder {
+  height: 100%;
+  display: flex;
+  flex-direction: column;
+}
\ No newline at end of file
diff --git a/web/app/cad/dom/uiPlugin.js b/web/app/cad/dom/uiPlugin.js
index 1d06ce50..ab4add98 100644
--- a/web/app/cad/dom/uiPlugin.js
+++ b/web/app/cad/dom/uiPlugin.js
@@ -15,18 +15,27 @@ export function defineStreams({streams}) {
       sketcherControl: state([]),
       sketcherToolbarsVisible: state(false)
     },
+    floatViews: state([]),
     sockets: {}
   };
 
 }
 
-export function activate({services}) {
+export function activate({streams, services}) {
   
   let components = new Map();
   const registerComponent = (id, Component) => components.set(id, Component);
   const getComponent = id => components.get(id);
   
+  let floatViewDescriptors = new Map();
+  
+  function registerFloatView(id, Component, title, icon) {
+    floatViewDescriptors.set(id, {Component, title, icon});
+    streams.ui.floatViews.mutate(views => views.push(id));
+  }
+  const getFloatView = id => floatViewDescriptors.get(id);
+  
   services.ui = {
-    registerComponent, getComponent
+    registerComponent, getComponent, registerFloatView, getFloatView
   }
 }
diff --git a/web/app/cad/expressions/Expressions.jsx b/web/app/cad/expressions/Expressions.jsx
new file mode 100644
index 00000000..fc85bd62
--- /dev/null
+++ b/web/app/cad/expressions/Expressions.jsx
@@ -0,0 +1,92 @@
+import React, {Fragment} from 'react';
+import ls from './Expressions.less';
+import cmn from 'ui/styles/common.less';
+import ToolButton from 'ui/components/ToolButton';
+import Fa from 'ui/components/Fa';
+import Row from 'ui/components/Row';
+import connect from 'ui/connect';
+import mapContext from 'ui/mapContext';
+import bind from 'ui/bind';
+import cx from 'classnames';
+import {actionDecorator} from '../actions/actionDecorators';
+import {combine} from 'lstream';
+import Folder from 'ui/components/Folder';
+import Stack from '../../../../modules/ui/components/Stack';
+
+@connect(streams => combine(streams.expressions.synced, streams.expressions.errors)
+  .map(([synced, errors])=> ({synced, errors})))
+@mapContext(ctx => ({
+  reevaluateExpressions: ctx.services.expressions.reevaluateExpressions
+}))
+export default class Expressions extends React.Component {
+  
+  state = {
+    activeTab: 'Script'
+  };
+  
+  render() {
+    
+    let {errors, synced, table, reevaluateExpressions} = this.props;
+    
+    const tabBtn = (name, icon) => {
+      return <ToolButton onClick={() => this.setState({activeTab: name})} pressed={this.state.activeTab === name}>{icon} {name}</ToolButton>; 
+    };
+    
+    return <div className={ls.root}>
+      <Row className={ls.switcher}>
+        {tabBtn('Script', <Fa fw icon='pencil' />)}
+        {tabBtn('Table', <Fa fw icon='table' />)}
+        {errors.length > 0 && <span><Fa icon='warning' className={cx(cmn.dangerColor, cmn.inlineBlock)} /></span>}
+        {!synced && <ReevaluateActionButton type='accent' className={cmn.floatRight}><Fa fw icon='check'/></ReevaluateActionButton>}
+      </Row>
+      
+      <div className={ls.workingArea}>
+
+        {this.state.activeTab === 'Script' && <Script reevaluateExpressions={reevaluateExpressions}/>}
+
+        {this.state.activeTab === 'Table' && <VarTable table={table} errors={errors}/>}
+
+        {errors.length > 0 && <Folder title={<Fragment><Fa icon='warning' className={cx(cmn.dangerColor)} /> Script Errors</Fragment>}>
+          <Stack>
+            {errors.map(err => <div key={err.line}>
+              line {err.line + 1}: {err.message}
+            </div>)}
+          </Stack>
+        </Folder>}
+
+      </div>
+      
+    </div>;
+  }
+}
+
+const ReevaluateActionButton = actionDecorator('expressionsUpdateTable')(ToolButton);
+
+const Script = bind(streams => streams.expressions.script)(
+  function Script({value, onChange, reevaluateExpressions}) {
+    return <textarea placeholder='for example: A = 50'
+                     className={ls.script}
+                     value={value}
+                     onChange={e => onChange(e.target.value)}
+                     onBlur={e => reevaluateExpressions(e.target.value)} />
+  }
+);
+
+const VarTable = bind(streams => streams.expressions.list)(
+  function VarTable({value}) {
+    return <table className={cx(cmn.fullWidth, cmn.stripedTable, cmn.delineatedTable)}>
+      <thead>
+        <tr>
+          <th>Name</th>
+          <th>Value</th>
+        </tr>
+      </thead>
+      <tbody>
+        {value.map(({name, value}, i) => <tr key={i}>
+          <td>{name}</td>
+          <td>{value}</td>
+        </tr>)}
+      </tbody>
+    </table>
+  }
+);
\ No newline at end of file
diff --git a/web/app/cad/expressions/Expressions.less b/web/app/cad/expressions/Expressions.less
new file mode 100644
index 00000000..fc208d5d
--- /dev/null
+++ b/web/app/cad/expressions/Expressions.less
@@ -0,0 +1,33 @@
+@import "~ui/styles/theme.less";
+
+.root {
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+}
+
+.script {
+  flex: 1;
+  resize: none;
+  background: inherit;
+  border: none;
+  color: #C4E1A4;
+  padding: 2px;
+  outline: none;
+  line-height: 1.8;
+}
+
+.workingArea {
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+}
+
+.switcher {
+  border-bottom: 1px solid @border-color;
+  width: 100%;
+}
+
+.toolBar {
+  
+}
\ No newline at end of file
diff --git a/web/app/cad/expressions/expressionsPlugin.js b/web/app/cad/expressions/expressionsPlugin.js
new file mode 100644
index 00000000..dcfdeb40
--- /dev/null
+++ b/web/app/cad/expressions/expressionsPlugin.js
@@ -0,0 +1,85 @@
+import {state, stream, merge} from 'lstream';
+import {indexArray} from '../../../../modules/gems/iterables';
+import {NOOP} from '../../../../modules/gems/func';
+
+export function defineStreams(ctx) {
+  const script = state('');
+  const list = state([]);
+  const table = list.map(varList => indexArray(varList, i => i.name, i => i.value)).remember();
+  const synced = merge(script.map(() => false), list.map(() => true));
+  ctx.streams.expressions = {
+    script, list, table, synced,
+    errors: state([])
+  };
+}
+
+export function activate(ctx) {
+  let _evaluateExpression = NOOP;
+  function reevaluateExpressions() {
+    let {varList, errors, evaluateExpression} = rebuildVariableTable(ctx.streams.expressions.script.value);
+    ctx.streams.expressions.list.next(varList);
+    ctx.streams.expressions.errors.next(errors);
+    _evaluateExpression = evaluateExpression;
+  }
+  function load(script) {
+    ctx.streams.expressions.script.next(script);
+    reevaluateExpressions();
+  }
+  function evaluateExpression(expr) {
+    if (typeof expr === 'number') {
+      return expr;      
+    }
+    let value = ctx.streams.expressions.table.value[expr];
+    if (value === undefined) {
+      value = parseFloat(expr);
+      if (isNaN(value)) {
+        value = _evaluateExpression(expr);
+      }
+    }
+    return value;
+  }
+  ctx.services.expressions = {
+    reevaluateExpressions, load, evaluateExpression
+  };
+  ctx.services.action.registerAction({
+    id: 'expressionsUpdateTable',
+    appearance: {
+      info: 'reevaluate expression script (happens automatically on script focus lost)',
+      label: 'update expressions',
+    },
+    invoke: ({services}) => {
+      services.extension.reevaluateExpressions();
+    }
+  })
+}
+
+function rebuildVariableTable(script) {
+  let varList = [];
+  let errors = [];
+  if (script == null) return;
+  let lines = script.split('\n');
+  let evalContext = "(function() { \n";
+  function evaluateExpression(expr) {
+    return eval(evalContext + "return " + expr + "; \n})()");
+  }
+  for (let i = 0; i < lines.length; i++) {
+    let line = lines[i];
+    let m = line.match(/^\s*([^\s]+)\s*=(.+)$/);
+    if (m != null && m.length === 3) {
+      let name = m[1];
+      try {
+        let value = evaluateExpression(m[2]);
+        varList.push({name, value});
+        evalContext += "const " + name + " = " + value + ";\n"
+      } catch (e) {
+        errors.push({
+          line: i, 
+          message: e.message
+        });
+        console.log(e);
+      }
+    }
+  }
+  return {varList, errors, evaluateExpression}; 
+}
+
diff --git a/web/app/cad/init/startApplication.js b/web/app/cad/init/startApplication.js
index 9b2b3706..a7755dc5 100644
--- a/web/app/cad/init/startApplication.js
+++ b/web/app/cad/init/startApplication.js
@@ -21,17 +21,17 @@ import * as ProjectPlugin from '../projectPlugin';
 import * as SketcherPlugin from '../sketch/sketcherPlugin';
 import * as ExportPlugin from '../exportPlugin';
 import * as TpiPlugin from '../tpi/tpiPlugin';
-
-import * as PartModellerPlugin from '../part/partModellerPlugin';
 import * as ViewSyncPlugin from '../scene/viewSyncPlugin';
 
+import PartModellerPlugins from '../part/partModelerPlugins';
+
 import context from 'context';
 
 import startReact from "../dom/startReact";
 
 export default function startApplication(callback) {
 
-  let applicationPlugins = [PartModellerPlugin];
+  let applicationPlugins = PartModellerPlugins;
   
   let preUIPlugins = [
     LifecyclePlugin,
diff --git a/web/app/cad/part/partModellerPlugin.js b/web/app/cad/part/partModelerPlugins.js
similarity index 55%
rename from web/app/cad/part/partModellerPlugin.js
rename to web/app/cad/part/partModelerPlugins.js
index bd369e9d..910e8d66 100644
--- a/web/app/cad/part/partModellerPlugin.js
+++ b/web/app/cad/part/partModelerPlugins.js
@@ -1,14 +1,11 @@
 import * as UIConfigPlugin from './uiConfigPlugin';
 import * as PartOperationsPlugin from './partOperationsPlugin';
 import * as DebugPlugin from '../debugPlugin';
-import {activatePlugins} from "../init/startApplication";
+import * as ExpressionsPlugin from '../expressions/expressionsPlugin';
 
-const PART_MODELLER_PLUGINS = [
+export default [
   UIConfigPlugin,
   DebugPlugin,
+  ExpressionsPlugin,
   PartOperationsPlugin
 ];
-
-export function activate(context) {
-  activatePlugins(PART_MODELLER_PLUGINS, context);
-}
\ No newline at end of file
diff --git a/web/app/cad/part/uiConfigPlugin.js b/web/app/cad/part/uiConfigPlugin.js
index 0edd2504..268778b5 100644
--- a/web/app/cad/part/uiConfigPlugin.js
+++ b/web/app/cad/part/uiConfigPlugin.js
@@ -2,6 +2,10 @@ import CoreActions from '../actions/coreActions';
 import OperationActions from '../actions/operationActions';
 import HistoryActions from '../actions/historyActions';
 import menuConfig from './menuConfig';
+import ObjectExplorer from '../craft/ui/ObjectExplorer';
+import React from 'react';
+import OperationHistory from '../craft/ui/OperationHistory';
+import Expressions from '../expressions/Expressions';
 
 export function activate({services, streams}) {
   streams.ui.controlBars.left.value = ['menu.file', 'menu.craft', 'menu.boolean', 'menu.primitives', 'Donate', 'GitHub'];
@@ -19,4 +23,8 @@ export function activate({services, streams}) {
   services.action.registerActions(HistoryActions);
 
   services.menu.registerMenus(menuConfig);
+
+  services.ui.registerFloatView('project', ObjectExplorer, 'Model', 'cubes');
+  services.ui.registerFloatView('history', OperationHistory, 'Modifications', 'history');
+  services.ui.registerFloatView('expressions', Expressions, 'Expressions', 'percent');
 }
\ No newline at end of file
diff --git a/web/app/cad/projectPlugin.js b/web/app/cad/projectPlugin.js
index 093c8e13..cad9061d 100644
--- a/web/app/cad/projectPlugin.js
+++ b/web/app/cad/projectPlugin.js
@@ -31,16 +31,20 @@ export function activate(context) {
   function save() {
     let data = {};
     data.history = streams.craft.modifications.value.history;
+    data.expressions = streams.expressions.script.value;
     services.storage.set(projectStorageKey(), JSON.stringify(data));
   }
 
   function load() {
     try {
-      let data = services.storage.get(services.project.projectStorageKey());
-      if (data) {
-        let history = JSON.parse(data).history;
-        if (history) {
-          services.craft.reset(history);
+      let dataStr = services.storage.get(services.project.projectStorageKey());
+      if (dataStr) {
+        let data = JSON.parse(dataStr);
+        if (data.history) {
+          services.craft.reset(data.history);
+        }
+        if (data.expressions) {
+          services.expressions.load(data.expressions);
         }
       }
     } catch (e) {
diff --git a/web/app/utils/errors.js b/web/app/utils/errors.js
index 7173cbd3..d0611dcd 100644
--- a/web/app/utils/errors.js
+++ b/web/app/utils/errors.js
@@ -19,4 +19,8 @@ CadError.KIND = {
   INTERNAL_ERROR: 'INTERNAL_ERROR',
   UNSUPPORTED_CASE: 'UNSUPPORTED_CASE',
   INVALID_INPUT: 'INVALID_INPUT',
-};
\ No newline at end of file
+  INVALID_PARAMS: 'INVALID_PARAMS'
+};
+
+CadError.ALGORITMTHM_ERROR_KINDS = ['INTERNAL_ERROR', 'UNSUPPORTED_CASE', 'INVALID_INPUT'];
+