Generic Bathroom Vent 3'' adapter

A friend brought over hiss generic no brand name bathroom vent needing an adapter to go to a 3" vent pipe. He couldn't find anything to fit it at the hardware store. There were slots in vent housing so I made locking tabs to press fit down into the tabs to secure the adapter to the housing. The adapter is 80X70x25mm rectangle to a 40mm length round 75mm base tapered to 73mm at the top. The taper is to allow the 3" pipe to slide on easily.The locking tabs are centered on the 80mm side, but on the 70 (well 69. I shaved 1mm for fit) the locking tabs are staggered to one side at 30mm. This adapter is unique to this vent. I highly doubt it's standard. I included the Fusion 360 files, but it would probably be easier to start over than to try and work with the rats nest I ended up making with this due to failing to measure properly thinking it was square at a glance.I made this out of PETG with 6 walls and 80% infill, It appears it'll hold up well even though I printed it