My turtle keeps flipping over
First of all, aren't there reptile forums out there that address this kind of situation? Please be sure to consult the turtle experts.

It's just that I don't know if anyone should recommend a part considering the challenges of mobility, ruggedness, and safety. Whatever solution this is must be 100% guaranteed not to shock or electrocute a poor little animal. 

But if something like this is truly the best path and turtle-based peripherals are still on the table, maybe you could just fashion a lightweight cone shape out of non toxic material and safely attach it to her back. And every time she rolls the cone forces her back onto her side.

edit: I noticed you have a 3D printer, you could model the cone to conform to the curves in her shell!