I had a book on float making, now long out of print. The author advocated using what he described as a body grinder. This was a piece of dowel (a bit of broom handle would do). He drilled a hole through the centre of the dowel large enough to fit a metal shaft (6in nail). The nail was araldited into the dowel. The nail was then placed into the chuck of a drill on a drill stand. The dowel was then shaped to the profile you wished the balsa body to be with a half round file, some of the dowel at each end has to be left at it's original diameter. Now for the clever bit. Take a piece of abrasive sheet and cut it to the exact length of the body shape you have just formed on the body grinder, make a series of cuts about an 1/8 in apart, stopping about a 1/4 in from its centre, offer this up to the body grinder and trim to the exact circumference of the body grinder then glue in place.
Skewer the piece of balsa on a bamboo barbecue skewer, with the body grinder spinning in the drill on the drill stand, offer the body to the grinder while revolving the skewer slowly between your fingers. when the skewer touches the bits of the grinder that are the original dia of the dowel no more grinding can take place, therefore you get a perfectly uniform size every time.
It may seem a little long winded, but the bodies only take a couple of seconds each to knock up once you have made the grinder.
The Author also used a jig to centre the holes he drilled in long lengths of balsa and used a modified drill press to force a blunt rod through the centre of the dowel.
I hope this may be of help to someone, if any points seem unclear let me know, I have used this method some time ago and it worked perfectly. The only down side is that you need a different body grinder for each float body shape.
