In slic3r there is thin-wall detection, so that thin walls get filled. I don't see that (yet) in simplify3d. How is it done? Here is the problem:It should have 100% infill, not hollow walls.
I'm using a Prusa I3 MK3. This is PETG.
This is the object being printed: https://www.thingiverse.com/thing:2812350