New project I have been working on:
A portable Lab laser with 650nm Red, 445nm Blue and 532nm Green primaries.
It is powered by two #18650 3400mah Panasonic cells for run times of over 2.5 hours.
(Or 9-12 VDC @ 1 amp plug-in supply)
Switches control White, Red, Blue, Green, Magenta...