2024-07-25: Dust was getting in where the print slots into the CPAP. The V3 design has a much tighter fit which should help alleviate the issue. I recommend adding tape around the connection where possible.
3M 2091 filters are about the same price as ResMed filters, but they are much larger and have filter ratings beyond just “Hypoallergenic”.
To install, first remove the filter door by opening it and carefully pulling it down near the hinges. This print should friction-fit into the opening. If it's loose, add a layer of tape to the outside of the part that goes into the filter slot.
Print with the bayonet side facing down and add supports around the bayonet. Print with a 0.2mm layer height.
For post-processing, remove the support material and the sacrificial bridging layer in the CPAP connection hole.
The author marked this model as their own original creation.