[Fathand]

Originally Posted by John Arnold

The cauls I use were bandsawn from 2X4's, so they are 1 1/2" wide. This allows the use of a go-bar deck. If you are using deep throat clamps, all you need is a flexible strip to protect the spruce from the clamps and to distribute the pressure. The strips that I have used are basswood that is 1 1/8" wide and 5/32" thick. Any soft, flexible wood will work. You can also use them on top of the bandsawn cauls if you don't want to bother with smoothing them.
BTW, I don't radius the tone bars and I clamp them flat. String tension will automatically pull some radius in the top below the bridge.
OTOH, you do need radius above the bridge to keep the top from going concave. String tension torques the bridge. While the design of X bracing stiffens the top between the bridge and soundhole, it still helps to have that little bit of radius.

Thanks for that