A Samus accessory for Sphero. The holes on the sides let you set it down without it rolling away. The groove down the middle doesn't seem to slow it down any. And it still charges.

Updated again: uploaded a solid model

Version 2.0 has vents to let the light through. Haven't tested it out myself yet.

Updated Version 2, so it should lay flat now

See the case in action here https://youtu.be/WFmooDpQu5A And my blogy post about it here http://samtastic.co/morph-ball/ Designed for the Make5000 contest.

Mirror the part, lay flat on the plate, and print out two halves. I didn't use support, and gave the inside some minor sanding.
I attached them with a few pieces of clear double-stick tape, and they held up to abuse until deliberately removed.