polyline p 4 0 0 10 0 0 10 0 10 8 0 10 8 0 4 6 0 4 6 0 6 4 0 6 4 0 0
mkplane f p
prism s f 0 5 0

OFFSETSHAPE 2 {} $calcul $type

checkprops result -v 1116

checknbshapes result -shell 1
