I liked the original design of the Celtic Skull Ashtray by @gfursu, however the alignment on the notches were a bit off so I decided to remake the ashtray using the base Celtic Skull model by @edoubleb.

Once the print is completed, just pop the metal shell of a tea light inside. It should fit very snuggly. I am unsure how standardized tea lights are, but the pack I bought from Walmart, Mainstays brand, were 38mm diameter and 11.5mm deep. If your tea lights have different dimensions, you may need to scale the model accordingly.