diff --git a/floorshapes.cpp b/floorshapes.cpp
index 5bb5be96..db77b7d2 100644
--- a/floorshapes.cpp
+++ b/floorshapes.cpp
@@ -773,8 +773,14 @@ void set_floor(const transmatrix& spin, hpcshape& sh) {
   qfi.usershape = -1;
   }
 
-int shvid(cell *c) {
-  if(geosupport_football() == 2)
+EX int shvid(cell *c) {
+  if(prod) {
+    int d;
+    cell *c1 = product::get_where(c).first; 
+    product::in_underlying_map([&] { d = shvid(c1); });
+    return d;
+    }
+  else if(geosupport_football() == 2)
     return pseudohept(c);
   else if(geometry == gBinaryTiling)
     return c->type-6;
diff --git a/geometry.cpp b/geometry.cpp
index 943e01d5..797167cc 100644
--- a/geometry.cpp
+++ b/geometry.cpp
@@ -272,6 +272,8 @@ hpcshape
 
   int SD3, SD6, SD7, S12, S14, S21, S28, S42, S36, S84;
   
+  vector<int> walloffsets;
+  
   vector<array<int, 3>> symmetriesAt;
   
   #ifndef SCALETUNER
@@ -311,6 +313,9 @@ hpcshape
   void make_sidewalls();
   void procedural_shapes();
   void make_wall(int id, const vector<hyperpoint> vertices, vector<ld> weights = equal_weights);
+  
+  void reserve_wall3d(int i);
+  void compute_cornerbonus();
   void create_wall3d();
   void configure_floorshapes();
   
diff --git a/graph.cpp b/graph.cpp
index 0f68c178..697f59d9 100644
--- a/graph.cpp
+++ b/graph.cpp
@@ -4524,6 +4524,7 @@ void radar_grid(cell *c, const transmatrix& V) {
   }
 
 int wall_offset(cell *c) {
+  if(prod) return product::wall_offset(c);
   if(penrose && kite::getshape(c->master) == kite::pKite) return 10;
   return 0;
   }
diff --git a/nonisotropic.cpp b/nonisotropic.cpp
index 394ee2f2..bc18703a 100644
--- a/nonisotropic.cpp
+++ b/nonisotropic.cpp
@@ -641,6 +641,36 @@ EX namespace product {
     dynamicval<geometry_information*> gc(cgip, underlying_cgip);
     return mscale(get_corner_position(c, i), exp(plevel * z/2));
     }
+  
+  EX int wall_offset(cell *c) {
+    int id = shvid(c);
+    if(isize(cgi.walloffsets) <= id) cgi.walloffsets.resize(id+1, -1);
+    int &wo = cgi.walloffsets[id];
+    if(wo == -1) {
+      cell *c1 = get_where(c).first;
+      wo = isize(cgi.shWall3D);
+      println(hlog, "generating a model for ", c->type-2, "+2");
+      int won = wo + c->type;
+      cgi.shWall3D.resize(won);
+      cgi.shPlainWall3D.resize(won);
+      cgi.shWireframe3D.resize(won);
+      cgi.shMiniWall3D.resize(won);
+
+      for(int i=0; i<c1->type; i++)
+       cgi.make_wall(wo + i, {product::get_corner(c1, i, -1), product::get_corner(c1, i, +1), product::get_corner(c1, i+1, +1), product::get_corner(c1, i+1, -1)});
+      for(int a: {0,1}) {
+        vector<hyperpoint> l;
+        int z = a ? 1 : -1;
+        for(int i=0; i<c1->type; i++)
+          l.push_back(product::get_corner(c1, i, z));
+        cgi.make_wall(won-2+a, l);
+        }
+
+      cgi.compute_cornerbonus();
+      cgi.extra_vertices();
+      }
+    return wo;
+    }
 
   EX bool product_sphere() { return ginf[underlying].cclass == gcSphere; }
   
diff --git a/polygons.cpp b/polygons.cpp
index 0bcdb028..a2b599c6 100644
--- a/polygons.cpp
+++ b/polygons.cpp
@@ -781,13 +781,16 @@ vector<hyperpoint> make5(hyperpoint a, hyperpoint b, hyperpoint c) {
   return {a, (a+b)/2, b, b+c-a, c};
   }
 
+void geometry_information::reserve_wall3d(int i) {
+  shWall3D.resize(i);
+  shPlainWall3D.resize(i);
+  shWireframe3D.resize(i);
+  shMiniWall3D.resize(i);
+  }
+
 void geometry_information::create_wall3d() {
   if(WDIM == 2) return;
-  int howmany = penrose ? 22 : prod ? S7+2 : S7;
-  shWall3D.resize(howmany);
-  shPlainWall3D.resize(howmany);
-  shWireframe3D.resize(howmany);
-  shMiniWall3D.resize(howmany);
+  reserve_wall3d(penrose ? 22 : prod ? 0 : S7);
   if(GDIM == 3 && binarytiling && geometry == gBinary3) {
     hyperpoint h00 = point3(-1,-1,-1);
     hyperpoint h01 = point3(-1,0,-1);
@@ -885,17 +888,7 @@ void geometry_information::create_wall3d() {
     }
   
   if(prod) {
-    cell model;
-    model.type = S7;
-    for(int i=0; i<S7; i++)
-      make_wall(i, {product::get_corner(&model, i, -1), product::get_corner(&model, i, +1), product::get_corner(&model, i+1, +1), product::get_corner(&model, i+1, -1)});
-    for(int a: {0,1}) {
-      vector<hyperpoint> l;
-      int z = a ? 1 : -1;
-      for(int i=0; i<S7; i++)
-        l.push_back(product::get_corner(&model, i, z));
-      make_wall(S7+a, l);
-      }    
+    walloffsets.clear();
     }
 
   if(GDIM == 3 && euclid && S7 == 6) {
@@ -991,6 +984,10 @@ void geometry_information::create_wall3d() {
     for(int i=0; i<isize(kv.first); i++) make_wall(i, kv.first[i], kv.second[i]);
     }
 
+  compute_cornerbonus();
+  }
+
+void geometry_information::compute_cornerbonus() {
   corner_bonus = 0;
   for(hpcshape sh: shWall3D) for(int i=sh.s; i<sh.e; i++)
     corner_bonus = max(corner_bonus, hdist0(hpc[i]));