: Joe Greenley has minicell foam for a good price, you would have to get it
: shipped.
If you have a local Wal Mart store see if they have any gardener's kneeling pads left in the gardening section. They are (were) 1x12x16 closed cell in green or pink (but you lose 3 inches off one end where they put the handle). I laminated 4 together, overlapping the joints, for each bulk head using 3M Spray Adhesive #80 for rubbers and vinyls, to make 2 inch thick bulk heads. You could get away with fewer pieces if you can tolerate more joints. They cut beautifully on the bandsaw. They were $2.97 a piece in North Vancouver but they have not restocked since I cleaned them out in the spring. I left a test piece fully immersed for 3 days to check the glue and the foam and found no glue failure and no water absorption. I know others have gone with 3 inch thick bulkheads but mine appear to have more than adequate strength.