Many years ago I visited Steve Dickenson's shop. While I have used the core or tube type bellows forms for odd sized or non hexagonal bellows, I much prefer these molds which are a close approximation of what he used from the old Wheatstone factory. They are not difficult to make out of wood, though I impregnated my one wooden version with wax to keep glue from sticking. They are meant to be used with the bellows frames mounted and an integral part of the bellows making process. The aluminum versions are great if you are making a lot of bellows. Steve's aluminum versions were cast metal,