A full set of 12 checkers with a concentric-ring bullseye face and a stacking design.

• 30 mm diameter, just under 7 mm tall, easy to scale up or down if you want.
• Two-color bullseye top, printed in one shot on an AMS. 
• Only one color change, so if you don't have an AMS you can add a single filament swap pause at the color-change layer and get the same result.

Printing

• Top and bottom are set to concentric infill so the rings come out clean instead of fighting the line direction.
• Bridging is slowed down for the recessed underside, so the bottom stays tidy for stacking without supports.