I've had a few goes at creating my own carvings as have other contributors, but I'll let them tell their own tales. Primarily it depends on the rock type. I've produced carvings using flint, antler (an old bottle opener made from an antler tip that I bought in a jumble sale). Both methods were quite successful. I've yet to try carving an igneous rock, I'll have to pick a lump up on my next trip to the Lakes.