I sand all the ribs together in 1 pack at same time to ensure they are all identical. By using a shaped template the blanks can be arranged with minimum wastage compared to rectangular blanks.

My hole punch has 2 different features to normal.
1 is a slot cut across the tube in addition to the normal sharpening of the inside ( this seems to help cut rather than crush the balsa. ) The punch is rotated about half a turn whilst pushing down on the balsa.
2 There is a smaller hole right thro the handle to allow the waste to be pushed out with a thin piece of stiff wire. ( obviously this hole is smaller than the tube so the tube is not pushed right thro the handle)

Yes, the Permagrit tool is similar to that shown in the photo.