4" dust collector magnetic port and adapter for my table saw (other tools coming, including DeWalt 735 planer)
I printed with 4 perimeters to ensure a good seal.
The magnets I used were a weird custom size (13.5 x 6 x 4mm - N48 - leftover from a project), but those slots are easily modifiable to something off-the-shelf.
I'll be playing with some improvements, including a dual-extruded TPU/TPE gasket for a air-tight seal.
STEP files attached.
7 second video showing it working
note: I printed in MatterHackers Ryno (it's a copolyester filament, similar to PETG filaments). I heat-set the magnets in place and used LocTite Plastic Bonder 2 part CA glue. They're firmly in place, but you may want to print in ABS or PLA to allow for easier adhesion. PETG/Copolyesters don't work with the vast majority of adhesives.