: This may or may not work, but I thought of something just now.. A family
: friend is always making flower arrangements and she uses some sort of
: florist's foam that you can press your finger into and it stays. seems
: like body weight sitting on it would leave quite an indention. It might be
: too stiff though, or possibly too easily crushed.. just a thought if you
: know anyone who does this, try a small piece out.

In the UK, that stuff is called Oasis, and it comes in small blocks. It's
really quite expensive, and unlikely you could get (or would want to pay
for) a big enough piece for a bum !

Andy