> In his book Nick recommends building the forms out of 1/2" plywood. I
> have yet to find a sheet that is not warped in some way. How do you
> flatten this stuff out so the forms are flat ??

I used 1/2" OSB for forms. It was about $10 or $11 for a 4x8 sheet (which I used a little more than have for Guillemot forms). Its been holding staples well, and it doesn't have any voids. Works much better than the plywood I used on the last boat.