It's covered in the polyhedron chapter in the manual: https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/The_OpenSCAD_Language#polyhedron -- View this message in context: http://forum.openscad.org/Preview-works-only-after-rendering-tp12109p12165.html Sent from the OpenSCAD mailing list archive at Nabble.com.