ive been building the second waterproof housing for powerful budget light
Fandayfire STL-V2 3XML 2x18650.
Simply putting the light into the aluminum pipe is too long for me.
so only the light head separated from body is used under water.
concept is simple but implementation is not so easy.
the head is in the large alumi pipe and four 18650 batteries (2s2p) in thin alumi pipes.