I present my small "Thresh" keychain tritium lantern, for use with a 3x11mm tritium vial (tritium vial not included).
This model has been scaled for printing in stainless steel, but is suitable for printing in all listed materials.
The attachment hole is 2.5mm wide, by 2.5mm high and is perfect for a 10mm split ring (not included).
Please be aware that this model is purposely rather spiky and may not be particularly comfortable when carried in a pocket.
The tritium vial 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.
There are some more photos of this object and other examples of my work, both 3D printed and otherwise, on my 'Tofty' facebook page.