I had a bit of an idea today.
I get blocks of eps 250mm x250mm x 1000mm at work so I was thinking if i made ribs like a hollow timber surfboard construction at these cross sections of a board & cut them out perfectly & say glued them all together with expanding foam maybe to fill the void were the ribs go & have say a couple of holes through the eps to allow for expansion of the foam .
I could then shape the board down to the ribs & get the right shape for the board .
Ive never made a board before & its the shaping that I'm worried about but I do have a scrolling saw that I can cut the ribs out perfectly with & I just scored a vacuum pump today & I sort of came up with this idea plus I get the foam for free .
Maybe just as a beginner guide to shaping a blank .
I realise it would add a bit of weight but if you used balsa wood for example & the rib was say only 20 mm thickness on the cross section & say 5 mm thick .
I think you would be able to cut ribs out of the centre of the timber as well so not using as much timber .
Make a stringer to mount all the ribs on & block out the voids & then sandwich it & glass.
It's probably a stupid idea but I had it & just thought I would pose it to people far more knowledgeable than me & see what they think .