Self-Supporting Roman Arch

PRINT:
1 Base
1 Wall
1 Keystone
6 Wedges
2 Knob Wedges
4 Straights

This is a simple archway I modeled. To assemble, take the four "straights" (pieces without any curvature, the ones with knobs) and stack two on each side of the base. Then take the two "knob wedges" (wedges with cutouts) and put one on each side. Lay the wall on a flat surface, arranging the Keystone and the rest of the wedges in their places. Hold them with your fingers while lifting the wall into place on the base.

The pieces aren't heavy enough and don't have enough friction to support themselves without the wall on the outside. If you have filament to waste, you could experiment making them 100% infill and see if that fixes the problem. Otherwise, don't fret! It looks cool enough with the wall attached. If you find the arch unstable, superglue is always an option, but then you lose the self-supporting aspect.