This adapter ring works with standard camera filter threads (~0.5mm depth, 0.7mm pitch). It adapts smaller diameter filters to work with larger diameter threads.
The thickness is as low as possible to reduce optical problems. Since there are threads on both the inside and outside of the adapter ring, I've made a tool for easy assembly: it uses six 2mm*20mm dowel pins, which fit inside the six holes in the adapter ring, to make it easy to thread and unthread from the filter threads.
Since the threads are fine and small, printing slow with sufficient cooling is needed: I'm using the Bambulab P1s standard PLA settings, but limited the maximum flow to 3mm^3s^-1 to slow down the speed.
Printing with PLA is recommended for high quality. Use <0.12 layer heights for better thread profiles. 0.4mm nozzle recommended.
The author marked this model as their own original creation.