Get a 1/2" square lathe tool blank and grind one end to a slight curve with a gentle rake and stone the bottom flat. Now you've got the perfect tool to slide along flat surfaces to deburr jagged edges left by drill bits. These tools have been around for at least 40 years but they've never had a handle. Press the tool blank into this holder and secure with a pair of M4 set screws. Push a length of 1/4" diameter drill rod into the hole in the back until it is snug against the back of the tool blank. For tough chip deburring smack the back of the drill rod with a small hammer while holding the tool blank flat and presto: a clean hole. This thing is particularly handy for holes that are too small to clean up with a Rout-a-Burr.