All-in-one FDM calibration model. This 5.1 x 2.8 x 5.9 in cathedral showcases fine layer finishing across five lancet windows per side, elegant flying buttresses at varied angles, slender 0.047 in spire tips and 0.094 in walls. Four colonnade pins nest into precise sockets alongside a captured bell. Six pieces.

A cathedral that is a torture test. One print, many tests. Five 0.47 x 1.2 in lancet windows per long side check bridging and pointed-arch self-support, three flying buttresses set at 65, 55 and 45 degrees form an overhang staircase, and tapered spires ending in 0.047 in tips push fine detail.

A clearance gauge built in. At the back of the base a tolerance colonnade holds four 0.2 in pins on a 0.47 in pitch, in sockets 0.24 in deep with per-side clearances of 0.006, 0.01, 0.014 and 0.018 in. Raised tally dots, 0.055 in across, count out which gap you are reading.

Parts, walls and clearances. The model prints as the cathedral body plus a captured bell in the crossing belfry, with 0.016 in clearance to floor and yoke and 0.024 in at the sides, and four separate colonnade pins. Nave walls are 0.094 in, the base slab is 4.7 x 2.8 x 0.31 in with a 0.079 in chamfer.