Ball Peen hammers do make nice tomahawks, they can be a bit tough to hammer out if you don't have a 3 or 4 pound sledge. I recommend starting with an old hatchet or small axe head for your first. Work on your hot rasping, rough shaping, annealing, normalizing, metal finishing and hardening skills. Once you get those right, then move on to using an older high carbon breaker bar segment, square stock, or round stock. This will require you to work on upsetting, drawing, widening, and fullering. Along with slitting or drilling and then drifting the poll hole in the head. If you have specific questions drop me a pm. I make a lot of them and can give you some ideas and steps to help you succeed on the first try.