I took a mini class with Mike Hosaluk who is incredible as an instructor, demonstrator and artist. He got most of us hooked on a hook tool he uses for end grain hollowing. I noticed that there are, in addition to Mike's son, 3 other sources of hook tools: a Mr. Martel in Canada, Hilton tools in the Ozarks, and a German maker of cryogenic hook tools. Do any of you have experience with these? I wonder what you think of them.