BMW 335D 4" air filter adapter

thingiverse

Fitting an open-element air filter to the 335D MAF is difficult; it's not round and the flange is too small, so most filters pop off or tear over time. This adapter fits snugly over the factory flange and accepts a couple of M5 threaded inserts to ensure it stays put. No special print settings are required. Pick a tougher / more heat-resistant filament as your engine bay can get pretty warm, PETG or ABS recommended. Print with supports on the bed for best results with the small overhang in the base flange.