On Thu, 9 Dec, 2021 at 11:27 AM, Leonard Martin Struttmann <lenstruttmann@gmail.com> wrote: To: openscad general discussion Gene, try making the wall an integer multiple of your nozzle size. For example, if you are using a 0.4mm nozzle, make wall=2.4; // an integer multiple of 0.4 Using a 0.28 layer height, Cura predicts 8 hours 23 minutes, 141 grams I just learned a lesson. After about 4 hours it finally got done with the solid top and started on the outer walls. And demo'd a bug in cura! It started an infill pattern of laying up at 45 degree angles, spaced about 2mm apart, filling the upper left corner and the lower right corner inside the box. And it was there on inspection of the preview in cura! I had left the wall at 2.5mm thick. So I reduced it to 2.4 from your hint, and that cleared the bug. So I played with the Z offset until I had a solid but hollow cube, the raised it .01 at a time until the top of the box opened up. Re-rendered in cura, the preview was clean, so I blessed the card with a fresh copy and restarted the printer. Cheers, Gene.