These tools are based on the ones that have been posted by Acer and Tallbear.
I made them out of .1875 O-1 drill rod. One side is flat and the backside has a radius. The cutting edge is also curved to use a rocking motion along a line.The largest tool is .115 wide and the smallest is .050 wide. The handles I bought at Midway USA. They are Grace screwdriver handles.