To extrude a part

Displace triangle nodes along a line that depends on their position relative to surrounding nodes

1. Select the part.
2. Click Modify > Manipulate Mesh.
3. Click Extrude along vertex normals.
4. Either click an area on the part or click and drag to create a custom region to extrude.
5. Click and drag the arrows that appear on the selected area to extrude the part.

This function makes use of the brush controls.