Hi Jon,

Making 3D printed parts that screw together is certainly possible, but getting high tolerance threads with an air tight seal is probably not practical with a hobby 3D printer.

I use a lot of 8-32" (~4mm) threaded brass heat inserts in my 3D print projects to join pieces. You just need to have a proper stepped hole in the model, and press the brass insert in with a hot soldering iron.

You could print a short, capped tube with air slots to hold the filter material, with an integral 4-bolt mounting flange at the base of the tube. Add 4 threaded brass heat inserts to the mask to accept the flange and machine screws. I visualize it looking like a tiny speaker grill with 4 mounting holes.

For an even better seal, make a round recess on the bottom of the flange to hold a rubber O-ring.

Ed Ferguson