CUTPOLY command is the only tool in GDL to make structural objects with variable profile in 2 dimension. In all the version of AC GDL, CUTPOLY cannot cut any shape with an internal angle bigger than 180 degree (concave). This is a big problem in many projects I worked on. I have to create my CUTANYPOLY macro which basically triangulates any concave shape to triangle and then issues the CUTPOLY command on each triangle. This is a really slow process but it works. I believe that somebody in Graphisoft must be able to fix that CUTPOLY command directly so that it would be much more efficient than my CUTANYPOLY macro.