Puzzle of the Pyramid

thingiverse

Place the 10 pieces so they form a pyramid. It's not as simple as it seems. To make printing possible without support or rim, the balls are not fully spherical, but have a small cylindrical base. My print: I used standard black PLA (RFPLCXEU01B) in my DaVinci Jr for the base plate. Quality was set to "Good". It took about 1 hour and 30 minutes to print, using 7.5 meters of filament (22.5 grams). For the 10 pieces, I used Neo Green PLA (RFPLCXEU0AD). Two were printed with "Good" quality (about 30 minutes), two with "Excellent" (about 1 hour 15 minutes), and six with "Excellent", but reduced infill from 30% to 10% (about 1 hour). I got the best results by printing them one at a time. Spoiler: The solution requires symmetry. It's a four-layer pyramid, starting with a 4x4 layer, followed by a 3x3 layer, then a 2x2 layer, and finally a single ball on top. No ball is placed directly on top of another. The balls in each layer are positioned between the balls below them. Each piece can cover one, two, or three layers. The solution can be described as 1111233112. The tricky part is 233: one row across and two standing on either side.