C-Flex calls for a similar male mould to that used to build a PVC cored hull except he frames have to be closer or intermediates used. Maximum recommended frame spacing is 18” (450 mm).  The frames are made in the same manner as for a cored hull and as the fore and aft battens are spaced at 4” to 6” [100mm to 150mm] apart, less are required than for a conventional mould.   Light battens (or strips of C-Flex) of 1” x 3/8” [25mm x 10mm] are placed vertically on each frame.   If you read the chapter on building a male batten type mould and consider the fact that you will use less fore and aft battens but will add some vertical battens, you will have an understanding of how to build a mould to support the C-Flex.   If you want more information, we recommend the book C-Flex by Barry Kennedy.