Plastic fabrication

Yes, use high density foam rubber.  Not styrofoam.

So we are discussing compressible foam?  And, the assumption is the rebound force is enough to keep the boat in shape?

Its compressible, but not 'super' compressible.  I know people that have built cedar strip kayaks that use it for bulkheads rather than wood so the hull has a little more give in case of a collision with a rock.  You can cut it rather easily with a saw and then fine tune it with coarse sandpaper.   When I made my seat, I used 80 grit on a disk grinder (or was it my orbital sander?).  It carves fairly easily.

Also, it is a closed - cell foam so it won't absorb water.

Dude, awesome info on the foam score.  It is amazing how much a price changes on a product, just based on what it's labeled use if for.  I love finding this kind of deal on multiuse products. Remind me sometime to tell ya the story about purchasing VW CV joints and stub axles for off road use. HUGE savings on that one.  

Now I'm curious

DAMHIK, but I can recommend against having a few to many 7&7's around the fire at elk camp and then tossing one of those into the flames....  

Fire is cool! Heh heh.


Nothing like a foam rubber inferno

So we are discussing compressible foam?  And, the assumption is the rebound force is enough to keep the boat in shape?

Its compressible, but not 'super' compressible.  I know people that have built cedar strip kayaks that use it for bulkheads rather than wood so the hull has a little more give in case of a collision with a rock.  You can cut it rather easily with a saw and then fine tune it with coarse sandpaper.   When I made my seat, I used 80 grit on a disk grinder (or was it my orbital sander?).  It carves fairly easily.

Also, it is a closed - cell foam so it won't absorb water.

It is good stuff.  Lots of Ocean kayakers use it form custom seats.  Good and durable!