NOTE: Scale STLs by 1000x in PrusaSlicer (Weird Bug)
Simple interlocking nozzle holders with a snug interconnecting fit, and loose fit between the printed part and the nozzle.
Labelled versions (0.8, 0.6, 0.4, 0.25) and unlabeled versions are available with labels written in micrometres; all the different sizes fit together.
The author hasn't provided the model origin yet.