I used Freecad to design a cartridge chute for a 40mm Bofors gun model. It is a 25mm quadrant 0.5mm thick with a U shaped cross section. Chitubox v1.7 fails to provide supports for it unless I really frig the rotation, and even when supports are shown the object remains grey rather than blue for printing. If I try printing the supports get printed but the object doesn't. I have printed items with some dimensions of 0.5mm or less. Can anyone explain why this is not printing? Is it simply asking too much?