Suppose I design a cube and choose a material that has a minimum thickness of x. As I understand it, if I put a hole in the cube, it will be fabbed hollow with all its faces x thick. But suppose I want each face the be 3x thick and solid (no powder between the inner and outer faces)? I can design an inner and outer cube, with a 3x gap between them and a hole through both so the inner-most powder can drain out, but why wouldn't that just create two cubes, one inside the other, both of whose faces are x thick and a gap of x between them? I assume the gap will either be powder or empty (causing the inner cube to rattle around slightly inside the outer one). How can I ensure this gap is actually solid, fused material? I asked this question of customer service and they referred me here. I use Alibre Design. Thanks.