I recently discovered the new 520nm green laser diodes that don't require the frequency doubling stage that regular 532nm green lasers need, which means I could finally build one as small as I wanted. I gutted a Nitecore Tube and turned it into a 30mW rechargeable green laser pointer with some extra firmware features.
Here's a video detailing the whole build:
It turned out so well that I ended up building a 450nm blue one too.