I present my triple tritium decorative bead, designed to take three of the 2.5x10mm tritium vials (tritium vials not included).
The central hole is 5mm in diameter and should just be wide enough for two lengths of 550 paracord.
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.