[sdiy] advice on creating power for small wearables? batteries ? solar ? Etc

[Dan Snazelle]

Hello 

I am working on a project that is quite small. I would love some advice on which coin or flat  batteries are good , small and have a decent output ..I would love to be able to drive leds, a 3.3v uprocessor, maybe a small speaker but of course AA batteries or a 9v are too big for this 

another possibility is a storage battery with a solar cell that continually charges the battery—I have never tried this and once again any advice would be great.

obviously it’s possible as the Apple Watch has quite a small footprint yet is able to drive a screen and a microprocessor. i suppose a tiny dc to dc converter could help
Too 

I see other examples all over the place I’ve just never been in a position where I needed something very small and instead of going through thousands of entries online I figured I would ask the community first 


THANKS FOR ANY HELP