The foamy bits are a closely guarded secret. They actually provide stealth battery power to the motor.
Actually, they're just adhesive-backed craft foam from Wally-world. :)
Yeah, the fabrication is the fun part. It just sucks that it came out like I wanted and I'm not gonna use it after all. I made it by rough cutting with a hacksaw, fine-cutting with a
nibbler tool, and then filing until pretty.