Ok, I created a structure that, if you look at it from a specific position, looks like an impossible triangle. I uploaded V1.1, and it would cost me around $45,-. Quite expensive for a first try, so i hollowed it out. Uploaded it again, and now it's over $70,-. What could cause this? Is it possible that in the hollowed out model, they automatically added supports or something, that make the volume grow? See att. v1.1 is the normal one, v1.11 is hollowed out.