I just came across the following page:
https://anthromod.com/blog/?p=98
Chris appears to have tried a number of rapid prototyping technologies and has started using the CNC/casting approach outlined at https://lcamtuf.coredump.cx/guerrilla_cnc1.shtml . That happens to be one of my favorite pages so I always look for reasons to link to it. You should check out both pages if you’re not familiar with the casting process.