i don't know alot about leather working, but i do know alot about steel. instead of using bolts, go to a junkyard and buy automotive coil springs. just run a plasma cutter or oxy/acelatene torch down opposite sides of the coil and you have a bunch of really long springs steel blanks for tool making that'll last 4ever. and if you want shorter handlse cut down 3 sides of the spring. depending on the spring itself you can get anything from really narrow pieces to really thick pieces. i use these tools on steel and they last a long long time. i usually forge them out by hand but if you are going to machine them you need to normalize the steel first to soften it. just heat it up to red/ just b4 yellow and burry it in the dirt for a few hours, or for an even softer working surface build a small campfire and a fan, build up the fire, throw in the steel, hold the fan on it, and then take the fan away in walk away. come backa few days later and they'll be as soft as butter. and then to re-harden after tooling heat the steel to a cherry red and drop into oil to quench. stamps made like this will last forever due to the high carbon content of the steel, and they should make good, sharp impressions year after year. hope that helps someone.