#J1----------------------------------------------
beziersurf bz1 3 3 \
0 0 0  0 10 0   0 20 0   10 0 0   10 10 0 \
10 20 0   20 0 0   20 10 0   20 20 0
mkface f1 bz1
prism rr f1 0 0 12
offsetcompshape rr rr -1
fsameparameter rr 0.001
box bx 5 5 10 10 10 10
bfuse f rr bx
nexplode f f
depouille result f 0 0 1 f_4 2 20 20 20 0 0 1

set square 1727.74