Man ... that's cool.

I too have a guitar in a case that doesn't fit snug. This might be a cool project to work on at a later date. The guitar tends to move around in the case, so this would work.

I'd very likely just trace out what I need and use my jigsaw to cut it out or use some of the foam I have and use a sharp bladed implement of some sort to carve it. Wood looks nice when it's polished and stained and it's tougher than foam.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.