Yeah, I'm bidding on a Star Wars AT TE or whatever (broken, but has five legs!) and my next solution would be to hit up the local toy store for legos/bionicle/etc. I just figured it's a decent idea, so I wanted to make sure I wasn't missing out.
It'd be slick to have a 3D pack of legs, shielding (not for the full hamster ball, but for the leg arms), maybe some thrusters, PPCs, antenna etc. A kind of one-stop kit. Buy your hamster ball and pick up the 3D printed kit of accessories...slap some plasticard on the ship and go for it.