Make your own 12 sided dice! No glue necessary!
To assemble, each opposite face should make a sum of 13, i.e. the number 12 should be on the opposite face of the number 1, the number 11 should be on the opposite face of 2, the number 10 should be opposite 3, etc…
Existing STLs will make dice that is approximately 54mm in diameter (yeah, it's kinda big) so scale accordingly.
The author hasn't provided the model origin yet.