diff --git a/web/app/3d/craft/brep/cut-extrude.js b/web/app/3d/craft/brep/cut-extrude.js
index 18fdaf3a..38bb69da 100644
--- a/web/app/3d/craft/brep/cut-extrude.js
+++ b/web/app/3d/craft/brep/cut-extrude.js
@@ -3,10 +3,12 @@ import * as math from '../../../math/math'
 import Vector from '../../../math/vector'
 import {Extruder} from '../../../brep/brep-builder'
 import {BREPValidator} from '../../../brep/brep-validator'
+import * as approx from '../../../brep/approx'
 import {subtract, union} from '../../../brep/operations/boolean'
 import {Loop} from '../../../brep/topo/loop'
 import {Shell} from '../../../brep/topo/shell'
 import {ReadSketchFromFace} from './sketch-reader'
+import {isCurveClass} from '../../cad-utils'
 
 import {BREPSceneSolid} from '../../scene/brep-scene-object'
 
@@ -35,6 +37,7 @@ export function doOperation(app, params, cut) {
       newFace.id = undefined;
     }
   }
+  approx.update(result);
   const newSolid = new BREPSceneSolid(result);
   return {
     outdated: [solid],
@@ -56,6 +59,7 @@ export class ParametricExtruder extends Extruder {
   constructor(params) {
     super();
     this.params = params;
+    this.approxIndex = new Map();
   }
   
   prepareLidCalculation(baseNormal, lidNormal) {
@@ -84,4 +88,14 @@ export class ParametricExtruder extends Extruder {
     }
     return basePoints.map(p => p.plus(this.target));
   }
+
+  onWallCallback(wallFace, baseHalfEdge) {
+    const conn = baseHalfEdge.vertexA.point.sketchConnectionObject;
+    if (conn && isCurveClass(conn._class)) {
+      if (!conn.approxSurface) {
+        conn.approxSurface = new approx.ApproxSurface();
+      }
+      conn.approxSurface.addFace(wallFace);
+    }
+  }
 }
diff --git a/web/app/3d/scene/brep-scene-object.js b/web/app/3d/scene/brep-scene-object.js
index 14a10003..251a237c 100644
--- a/web/app/3d/scene/brep-scene-object.js
+++ b/web/app/3d/scene/brep-scene-object.js
@@ -1,4 +1,5 @@
 import Vector from '../../math/vector'
+import {EDGE_AUX} from '../../brep/approx'
 import {Triangulate} from '../../3d/triangulation'
 import {SceneSolid, SceneFace} from './scene-object'
 
@@ -40,7 +41,9 @@ export class BREPSceneSolid extends SceneSolid {
       for (let halfEdge of face.outerLoop.halfEdges) {
         if (!visited.has(halfEdge.edge)) {
           visited.add(halfEdge.edge);
-          this.addLineToScene(halfEdge.vertexA.point.three(), halfEdge.vertexB.point.three(), halfEdge.edge);
+          if (halfEdge.edge.data[EDGE_AUX] === undefined) {
+            this.addLineToScene(halfEdge.vertexA.point.three(), halfEdge.vertexB.point.three(), halfEdge.edge);
+          }
         }
       }
     }
@@ -55,6 +58,7 @@ class BREPSceneFace extends SceneFace {
     super(solid, brepFace.id);
     brepFace.id = this.id;
     this.brepFace = brepFace;
+    brepFace.data['scene.face'] = this;
   }
 
 
diff --git a/web/app/3d/selection.js b/web/app/3d/selection.js
index fc655f67..09e3dede 100644
--- a/web/app/3d/selection.js
+++ b/web/app/3d/selection.js
@@ -1,4 +1,5 @@
 import DPR from '../utils/dpr'
+import * as approx from '../brep/approx'
 
 class AbstractSelectionManager {
   
@@ -81,9 +82,10 @@ export class SelectionManager extends AbstractSelectionManager {
   
   select(sceneFace) {
     this.clear();
-    if (!!sceneFace.curvedSurfaces) {
-      for (var i = 0; i < sceneFace.curvedSurfaces.length; i++) {
-        var face  = sceneFace.curvedSurfaces[i];
+    const group = this.findGroup(sceneFace);
+    if (group) {
+      for (var i = 0; i < group.length; i++) {
+        var face  = group[i];
         this.selection.push(face);
         setFacesColor(face.meshFaces, this.readOnlyColor);
       }
@@ -98,6 +100,17 @@ export class SelectionManager extends AbstractSelectionManager {
     this.viewer.render();
   }
   
+  findGroup(sceneFace) {
+    if (sceneFace.curvedSurfaces) {
+      return sceneFace.curvedSurfaces;
+    }
+    const approxFace = sceneFace.brepFace.data[approx.FACE_CHUNK];
+    if (approxFace) {
+      return approxFace.faces.map(f => f.data['scene.face']);
+    }
+    return undefined;
+  }
+  
   deselectAll() {
     this.clear();
     this.viewer.bus.notify('selection', null);
diff --git a/web/app/brep/approx.js b/web/app/brep/approx.js
index b73722cf..574c6532 100644
--- a/web/app/brep/approx.js
+++ b/web/app/brep/approx.js
@@ -1,8 +1,10 @@
-const FACE_CHUNK = 'approx.face.chunk';
-const EDGE_CHUNK = 'approx.edge.chunk';
-const EDGE_AUX = 'approx.edge.aux';
+import {DoubleKeyMap} from '../utils/utils'
 
-class ApproxSurface {
+export const FACE_CHUNK = 'approx.face.chunk';
+export const EDGE_CHUNK = 'approx.edge.chunk';
+export const EDGE_AUX = 'approx.edge.aux';
+
+export class ApproxSurface {
   constructor() {
     this.faces = [];   
   }
@@ -11,9 +13,14 @@ class ApproxSurface {
     face.data[FACE_CHUNK] = this;
     this.faces.push(face);
   }
+  
+  clear() {
+    this.faces = [];
+  }
+  
 }
 
-class ApproxCurve {
+export class ApproxCurve {
   constructor(surface1, surface2) {
     this.surface1 = surface1;
     this.surface2 = surface2;
@@ -37,8 +44,20 @@ class ApproxCurve {
   }
 }
 
-function update(shell) {
+export function update(shell) {
   const index = new DoubleKeyMap();
+  for (let face of shell.faces) {
+    const approxSurface = face.data[FACE_CHUNK];
+    if (approxSurface) {
+      approxSurface.clear();
+    }
+  }
+  for (let face of shell.faces) {
+    const approxSurface = face.data[FACE_CHUNK];
+    if (approxSurface) {
+      approxSurface.addFace(face);
+    }
+  }
   for (let e of shell.edges) {
     const face1 = e.halfEdge1.loop.face;
     const face2 = e.halfEdge2.loop.face;
@@ -55,7 +74,7 @@ function update(shell) {
   }
 }
 
-function getCurve(index, o1, o2) {
+export function getCurve(index, o1, o2) {
   let curve = index.get(o1, o2);
   if (curve == null) {
     curve = new ApproxCurve(o1, o2);
diff --git a/web/app/brep/brep-builder.js b/web/app/brep/brep-builder.js
index a729e261..9f2f477c 100644
--- a/web/app/brep/brep-builder.js
+++ b/web/app/brep/brep-builder.js
@@ -38,7 +38,6 @@ export class Extruder {
   }
   
   extrude(basePoints, normal) {
-    basePoints = checkCCW(basePoints, normal);
     const baseLoop = createPlaneLoop(basePoints.map(p => new Vertex(p)));
     const baseFace = createPlaneFace(normal, baseLoop);
     const lidNormal = normal.multiply(-1);
@@ -72,6 +71,7 @@ export class Extruder {
       
       const wallFace = createPlaneFace(wallNormal, wallLoop);
       wallFace.role = 'wall:' + i;
+      this.onWallCallback(wallFace, baseHalfEdge);
       
       shell.faces.push(wallFace);
     }
@@ -90,6 +90,9 @@ export class Extruder {
     shell.faces.forEach(f => f.shell = shell);
     return shell;
   }
+
+  onWallCallback(wallFace, baseHalfEdge) {
+  }
 }
 
 export class SimpleExtruder extends Extruder {
diff --git a/web/app/brep/operations/boolean.js b/web/app/brep/operations/boolean.js
index 3a52f88e..eae67a04 100644
--- a/web/app/brep/operations/boolean.js
+++ b/web/app/brep/operations/boolean.js
@@ -619,6 +619,7 @@ export function loopsToFaces(originFace, loops, out) {
   function createFaces(nestedLoop, surface) {
     const loop = nestedLoop.loop;
     const newFace = new Face(surface);
+    Object.assign(newFace.data, originFace.data);
     newFace.outerLoop = loop;
     loop.face = newFace;
     out.push(newFace);
diff --git a/web/app/utils/utils.js b/web/app/utils/utils.js
index 4c6c6fba..ff8e553f 100644
--- a/web/app/utils/utils.js
+++ b/web/app/utils/utils.js
@@ -78,11 +78,11 @@ export class DoubleKeyMap {
     if (subMap == null) {
       subMap = this.map.get(b);
       if (subMap != null) {
-        return subMap.get(a);;
+        return subMap.get(a);
       }
       return null;
     }
-    subMap.get(b);
+    return subMap.get(b);
   }
 
   set(a, b, value) {