I am working on a dagger that will have a fuller groove and needed a groove cutting tool. So I built one out of 1/2" square mild steel. The bit is 1095 and interchangable. I turned the square bar to 3/8" round and peened a scotch broom wood handle between two steel caps.
The guide bar is adjustable from 1/8" out to 1 3/4".
It also takes 1/4" and 3/8" lath chisels.