: I once used puzzle mats from Harbor freight to make a seat. It's
: closed cell foam. But it was also difficult to glue with
: Weldwood contact cement ... the volatile variety ... the glue
: didn't wanna stick to the foam ... and it was pure heck to shape
: using everything including sand paper, Dragon Skin, Sureforms,
: belt sanders, grinders and rasps. I could score the heck out of
: the surface but the little strands of foam just held on for dear
: life and were very difficult to abrade off ... never seen
: anything like it. I'd say it took 3 or 4 times longer to shape
: than mini cell. So if anyone wants to try it ... don't use the
: same stuff I used.

: Ken Blanton

That was what first appealed to me about trying this approach. I didn't have to use anything the sculpt the surface, either on top or underneath. Square edge strips glued on the underside feel quite comfortable through the top layer.

The finish on previous seats built using the normal method of shaping the top surface was OK, but the surface was not as good as the untouched surface with this method.

As it turned out, when I decided the belt sander would be a quick way to adjust the width of the outside rails, it sanded very well.