Somebody was looking for some campaign skulls, and I couldn't find any high quality ones with the symbols embedded, so I decided to make them. So far all of the ones from Halo 3 have been made. They can be found here:
https://www.thingiverse.com/thing:4916304
I didn't plan to paint the model at first, but the print slightly warped so I filled the gap with body filler, and after that decided I might as well finish it!