Which brands or models have a mechanical design that is easy to customize?

[mjbmikeb2]

Is something like a Convoy a good place to start?

My plan is to make a light with a more advanced user interface than what you can get today.
I would like to keep the circular LED/Reflector head assembly intact but add a rectangular battery box that has room for a driver board, ESP32 microcontroller, a LCD/LED display, magnetic switches and wireless charging coil.

 

[letschat7]

I would start with a Streamlight JR. It is very modular.