I was checking out the Instructables" website at anything they might have seat covering related and ran across this stuff. Kinda cool if you could build a mold but then again you could have a big rectangle and use that and then just carve or whatever to create the shape you need.
Rigid and Flexible Castable Foams | Smooth-On, Inc.
Definitely cheaper to buy a chunk of foam but i still thought this stuff was cool. Reminds me of the stuff used in making monster costumes and puppets etc in movies.
Deb