I printed this upright with manual support under the arch (probably not necessary but I wanted to try the manual option). Printed with Elegoo Rapid Black PETG, .2mm layer height, .4mm nozzle, recommended plate and filament temps.
The author remixed this model.
Extended the top up 20 mm and moved the holes up as well. I tried to redo the fillets but Fusion complained and I'm not skilled enough to overcome those challenges. I've included the F3d file if someone wants a challenge! I used 2 ea 6mm x 20mm and 1 ea 6mm x 16 mm flat screws.