Years ago, I made my hammer blades with the help of my wife's grandfather. Together (mostly him) we fashioned them out of my extra lawn mower blade! Today, I've designed them out of the same material (4140 alloy steel). I'm not a fan of the bent structure of most hammer blades, as I feel it loosens the dirt from the very first step. So, I've designed a laser cut, laser etched hammer blades with multiple holes and carriage bolts to fit any boot sole (initial grinding even done by yours truly).