Extruding an object from two surfaces


I have two zero thickness surfaces that I want to merge together to create one solid object. The front part I can easily extrude to the required thickness but to join the curved surface at the back (left on the pictures) to the flat surface below seems to be more difficult as the vertices need to be extruded to different heights

Any help or suggestions would be much appreciated.



  1. Put the models above each other and join them so that they are a part of the same object.
  2. Select the outer edge loop on both parts
  3. Press ‘f’ -> ‘skin edge-loops’ (or something like that)
  4. done

You might wanna make sure you have an equal amount of vertices around each object. This isn’t necessary, but it will give a cleaner mesh.

This won’t work in blender 2.5 as the skin edge loops function hasn’t been added yet (or has it?)

IT has not, but it appears he’s using 2.49 anyway.
Anyways, how did you end up with so many vertices?
It would be easier to join them with a simpler model.

Thanks for the help, I’ll try it out. They’re some .stl files that I’ve been given to work with, I agree, far too many vertices!

I don’t suppose there’s a shortcut for selecting the entire outside edge of the shape rather than selecting each edge in turn?

In the select menu there are other options for selecting vertices.
Try out the edge loop, and ring.
Select Non Manifold might help, but it’s hard to say with .stl.
Try out Non Manifolld, CTRL SHIFT ALT< +M

For reducing the vertex count on this type of model, I’d suggest you use retopo to rebuild a new mesh on top of the old one. That way you can easily match the top to the bottom.

I would rough out a low res mesh to the same outline as the model, extrude it to form a top and bottom face, then retopo or shrinkwrap the top face of the new model to the top mesh, and the bottom face to the bottom mesh.

EDIT: Also, looks like you are modelling a shoe sole, so think about making the heel flat to start with, and then extruding it separately out of the bottom face of the sole. Otherwise you will end up with some very stretched mesh around the join between the sole and heel. Extruding an object with a step in it can be very troublesome otherwise.