I have never made one and can't seem to find any plans or help to point me in the right direction. I've made a few selfbows but have never put them in a caul, well because I don't have one. Anyone have any plans, drawings or help to point me in the right direction.
There is some talk of dimensions on the DVD Rattlesticks by Gary Davis. But you'll probably get some advice here eventually..
Wish I could help but I've not built one either.
Yet....
TBB (vol. 2?) has some good pics of cauls in the wood bending and/or recurve sections.
Here is a link to a thread on how to make a caul:
http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=001885#000006