A light that never turns off and can be used to read a book at night fueled by radioactive decay - once eyes have adjusted to the dark for a while.

A single tritium light is not really bright enough to see with. So to step things up, 5 were used. Two are green as they seem to be the brightest and 3 white - to make it a bit more pleasant to see by. Then a parabolic reflector was placed around each one to focus the light from a 360 ° spread to something like a 90 ° splodge.

In theory, this could give an apparent brightness of 20 times that of a single tritium vial without a reflector. No idea if that was achieved, but certainly much, much brighter.

To assemble:
1) Print bits
2) Use aluminium tape to make reflector (fussing about a bit to keep it neat)
3) Insert tritium vials (which should be a loose fit) and glue together
4) Find some clear plastic and cut to size for the window - if careful, it'll stay in without glue

Safety note - do not break tritium vials.

The vials came from the obvious popular auction site and are 22.5mm x 3 mm.

There are 2 holes in the side of the light that can be threaded to suite M3 screws for mounting if desired.

I put this in the Art category as it's expensive and not overly useful.

Ultimaker

Ultimaker 2

No

No

0.15 (or better)

Whatever