Back in 2015, I finalised an idea that I had in mind for many years. I wanted to drill my Eltharion on Stormwing miniature and insert a metal piece between the High Elf and the Griffon so that it held better.
Eltharion and Stormwing - Drilled and ready
When I broke it by inadvertence in 2015, it gave me the perfect opportunity to drill the model. I used the smallest bit that I have for my drill. I drilled about 1.5 mm inside of the miniature and 1.5 inside the griffon. Then I took a paperclip and cut it to roughly 3 mm. I verified that it fit well and cut a tiny bit more if necessary.
Eltharion and Stormwing, 4th Edition Warhammer
Finally, I made some epoxy glue, which I prefer for metal on metal. I dipped the 3 mm paperclip piece in the glue and then placed the glue-covered part in the griffon. Then I carefully applied some glue under Eltharion and also on the part of the paperclip that stuck out of the griffon and then joined both pieces together.
In the future, I must upload a "finished" photo in this post. Thanks for reading!
(Edit: Here is the final model photographed outside in 2021)