Assuming that your tumbler shaft is 1/4", the quickest & easiest way to do this is to take a piece of 1/2" tool steel that is 1 inch long and drill a 11/32" hole 1/2 the way through the stock. Drill an appropriate sized hole that will allow you to thread for whatever size rod you are using for a handle on the opposite end, then tap the handle hole and screw the handle in place. Take a length of 1/4" key stock and insert it into the 11/32" hole after the socket has been heated bright red and hammer the sides to fit around the key stock. Go carefully here as you do not want the key stock to become stuck or the sides lop-sided. An alternate method would be to cold forge the sides around the key stock. (Both methods work well, I find out.) Bend the handle to suit, clean it up and then harden the whole thing. It may not be pretty, but it's a lot cheaper than what is sold and it's comfortable. Hope this helps, Bookie