This is a small keychain tritium lantern for use with a 3x22.5mm tritium vial (tritium vial not included).
As well as the tritium vial, a clear plastic spacer tube is required to fill the void between the tritium vial and inner wall of the holder body (not included).
The tube's dimensions should be around: 21mm long, 6mm OD, 3.1mm ID (due to the varying final dimensions of different materials the tube dimensions are approximate and may need adjusting).
The attachment hole is 2mm wide and is perfect for a 10mm split ring (not included).
The tritium vial and clear spacer tube should be set using a UV activated optically clear adhesive such as Norland 61 or Loctite glass bond. These adhesives will cure in direct sunlight in an hour or so.
This model has been updated, with a slightly larger head diameter, to allow printing in alumide.
I have a few assembled tritium lanterns in stainless steel available from my Etsy shop
(tritium vial glued in place with Norland 61 and split ring installed).
There are some more photos of this object and other examples of my work, both 3D printed and otherwise, on my 'Tofty' facebook page