I tried inserting a spent motor casing into a BT-20 and using a pipe cutter. It is AWESOME! You cannot tell which end was cut. This is not my opinion, but everyone in our little club that I showed it to. Now to get dowels of appropriate lengths and sizes for the other tubes.

Works very well on thin tubes, if you have a large enough tubing cutter. Unfortunately, it tends to dull the cutter fairly quickly. So, I wouldn't do this on a "production" basis. Cardboard is actually very hard on blades.

EB, TS, and RD in rec.models.rockets