The stls for exterior and frame on bb8 builders club. Give them time, they will accept you. Join joes drive, vonjet bb8 sphere, daver's RCD and droid designs on facebook for more options for driving mechanism. 2 last are in beta testing stage but look like very beautiful mechanisms. Joes drive is well tested and looks like it works but I prefer other 2 for clean and compact build. If you want it rolling, I guess injection molded frame will be a good base. I would also consider vonjet design where you don't need inner frame. I would go this route if I was just starting. I didn't like that panels could shift and move little when attached to frame and the big gaps appeared. It was probably caused by my resin cast and slightly flexible panels.
RE: The Dublinmaker, annual event for makers in Ireland