I made my first 3D object in MatterHackers MatterControl2.0.
It is half a skeleton of a cube made out of joined, overlapping, right-triangle prisms, with holes drilled through the 4 bottom corners. The middle is all empty space.
I exported it to .STL, and opened it in Simplify3D.
It looks all right in initial view:
, but in prepare to print, it fills the bottom middle up with stuff:
I have Skirt/Brim checked, but the other check boxes on the Additions tab are unchecked.
What is going on?