Tritium vial holder ( 25mm x 3.5 mm )

thingiverse

Tritium is radioactive hydrogen - it's also called H^3. It's a byproduct of reactors and when you put it into a tube lined with phosporus it gives off a glow that's a bit dimmer than a fluorescent glow stick, except that it stays lit for decades. You can buy tritium vials on etsy and Ebay and Alibaba. In the US they can be hard to find because selling them requires a license from the Nuclear Regulatory Commission but they are used in fancy watches and on gun sights and as far as I'm aware they aren't illegal. In other countries, like the UK among many others, they are not too hard to buy. Check with your local laws before buying one. They usually sell for less than USD$20. This thing is a 3D printed tritium vial holder that protects the glass and also - I think - looks pretty cool. There are lots of vial holders out there for 3x22.5mm vial sizes but this one is for the larger 25mm x 3.5mm vials which are larger and emit a bit more light. It's coded in OpenSCAD so if you want to resize it, you can. I printed in <10 minutes on my Printrbot Simple Metal on 0.2mm layer height without support. Print one of each .stl. One question that lots of people - like my wife - ask me is "if it's radioactive, is it safe" and the answer is "yes, it's totally safe." Tritium emits beta particles which are electrons. I have a Geiger counter and you can see that there's no measurement when the vial is more than ~5cm away from the detector. So 5cm (2 inches) of air is enough to stop any radioactivity. If you stick a piece of paper between the vial and the detector, the paper is enough to stop it. The radioactivity from tritium vials is on par from old CRT monitors (which also shoot electrons at phosphorus on glass to produce a glow) These particles are too weak to penetrate human skin at all. If you ate the vial, that would likely not be good. But there are a whole lot of cleaning supplies around a house that also wouldn't be good to eat.