Thinking about this accessibility issue and internal power supplies, has anyone ever played around with rechargeable battery packs inside the model with a small micro-USB recharge port hidden under a removable panel or feature somewhere? True, nothing would be easily accessible if something went wrong but there could be no light leaks and everything would be really secure. Just a thought.
Ah ha, that might just be the answer. But along with a mini- USB charge port, I'm thinking the small arrow head shaped insert piece is a perfect candidate for a magnet attached removable panel. Also you could glue the top of the wedding cake deck lid down with something like white Gator glue. It's strong enough to hold, will seal any light leaks and can be cut easily around the perimeter with an xacto blade to remove the top in case of the need for serious repairs. I think that's worth a look to see how it would go together.
Bill
Edited with after thoughts. ORRRR you could MAYBE find batteries small enough to fit down inside that arrow shaped piece's hole. Then you could forgo the USB plug altogether and have a removable battery pack. Surely there must be some batteries that could fit in there, it's a decent sized hole.