: I built a solid 2x4 beam out of interleaved 4" wide strips of
: 1/2" plywood. I staggered the joints in each layer by 2'
: and it is solid as a rock. And it's not to heavy either. If you
: reduce the dimensions by 1/4" in each direction (1
: 3/4" x 3 3/4") you have room to move your forms
: around.

Mine's done the same way, using Tom Yost's ideas. It's three 2x4's wide bolted about every 6" and has a 1x6 on top that's just drywall screwed in place. I can fairly easily move it around, have taken it to the two classes I've taught so far on the roof of the car. Can also be extended to most any length you'd want, though at 16' it works on most boats up to around 20'.

Bill H.