Had done this before with a n old polystyrene coolite and sanded away at the rails etc untill it became a shape i liked.
i then painted the foam with a strong water resiliant two pack epoxy paint.
wasnt bad.
Problem is coolites sre too small for most of the designs you want to try also finning them might be tricky with skills...
any ideas? or further thought
Never thought of doing that,Lots of good opportunities. At least you got some shaping fun ?
I’ve often thought about using a heat shrink plastic to seal the board, may even add some strength given the right platic (the one that sets hard like used for packaging toos/toys etc). This would be a great way of rapid prototyping and testing for a more permanent design.