You'll definitely want to bump thickness up to 2.0 mm for more rigidity. Otherwise just measure the diameter of your filter and maybe round up slightly. I put

You'll definitely want to bump thickness up to 2.0 mm for more rigidity. Otherwise just measure the diameter of your filter and maybe round up slightly. I put a layer of electric tape around the flange where the filter adapter inserts into the filter and it makes a very nice airtight fit. Finally, just print it with the big end facing down and you shouldn't need any supports. screwhole=5; // fan screw hole diameter (5) filterhole=59; // HEPA filter hole diameter thickness=2; // Thickness of plastic layer (1.5) insert=10; // Length of insert into filter (10)