I got one of these to make a shift knob for my truck. I drilled out the bottom of the head, and attempted to tap it with a tap. But the material that it's made of turns into a powder when you drill it. So when I attempted to tap it, the threads wouldn't hold, they just kept breaking. so I was thinking I could fill the hole I drilled with a resin of some kind and then redrill it and tap that. Any ideas?