Slash McCoy
I freehand dog rockets
This. The best way. There are two keys to the success of the modern pasted balsa technique. One is abrasive that is deeply embedded in a lapped substrate instead of rolling around on the surface. The other is lots of laps and VERY light and balanced pressure. You can't get pressure that light if you are resting the balsa horizontally on a fixed surface. The floatier, the better. If you don't do it in hand, you may as well not even do it at all because you are not appreciably improving a good 12k or 20k synthetic edge.
