TopMod is often fiddley / finicky. One trick I use is to do my base extrusions in other programs less fiddley: Blender, 3dsMax, Modo (I don't have, you might), Wings3d and such.
Another thing I do, since I don't have windows, is install via virtual machine, or on a Linux box, run using WINE or PlayonLinux, and store in email (attachments) as drafts - accessible from outside the VM.
Creative and Innovative is the name of the game.
This, for example from MathGrrl's Clover Knot - Thingiverse. Tweaked in Blender:
imgur.com/a/zi64A64