BB-8 remix with dummy internals

I was as excited as anyone when I found out they built practical, working BB-8s for the new Star Wars, but I'm not really "$150 toy" excited, and I can't really even justify spending $50 on a used Sphero to cut open, so I decided to build upon the work that's already been done here on Thingiverse. My goal was to build a BB-8 using only printed and hardware store parts that could roll along the floor and keep it's head upright, and spoiler alert: it finally works! https://www.youtube.com/watch?v=bYBuFEJ_PQc

I made some initial modifications to the existing parts, adding holes for 1.75mm filament in the ball halves so it could snapped open and closed (repeatedly) and in the head to make antennas.

The hardware store parts are 19mm ceramic disc magnets (same as the ones for Google Cardboard, left over from that build), 9 7/16" ball bearings (the biggest they carried), 2 8mm OD/3mm ID/4mm wide roller bearings from old spring-loaded extruders (and technically, a hobby store and not a h