we almost need a sub-forum for this topic
would love to see what people have done for cases, for this. I'm thinking of making some and still collecting ideas.
looks like the banana jack idea is popular so I will add that to my to-do list. was also thinking of having it be Qi rechargeable via simple credit-card style adapters like these:
https://images-na.ssl-images-amazon.com/images/I/61V8AbhnLNL._SL1200_.jpgyou get a simple 5v out from the micro usb connector. cut it off, tap into it and go into a TP4056 lipo charger board, then use any 3.7v lipo battery. that's the charging side.
then, you need a step-up, such as this:
https://www.amazon.com/Control-Converter-Module-Charger-0-9V-5V/dp/B01FDD3AYQthat will get you back to 5v from the lipo. after that, you don't need the 5v regulator chip anymore in the circuit.
not sure how clean the psu output will be - might need some filtering.
put the Qi coil on the very bottom of the case and use thin plastic to cover it. 1/8" is ok but thinner is even better. then you simply lay the box into a Qi cradle and that's the charging solution. this cradle is nice since it lets you center the coil on the sender side:
https://www.amazon.com/gp/product/B0177SPJP8/it has a knob on the back that lets you raise/lower the coil, so once you build your coil rx into your box, you align the 2 coils with the knob on the stand. it works pretty well and is good fun for DIY.