I present my "Barbell" tritium vial holding decorative bead, designed to take six of the 2x6mm tritium vials (tritium vials not included).
The central pin is 5mm in diameter and 6mm wide.
The tritium vials 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.