This is a 3D-printable adapter plate for attaching ducting to the Nutone HB80RL bathroom exhaust fan (or similar models). I used it to install custom ducting for a Craft Room ventilation system.

The adapter includes:

• A circular outlet for connecting to 3D-printed or flexible ducting
• Mounting holes intended for M3 heat-set inserts
• Recesses sized for a small socket wrench to help with installation

Notes on installation:

• The fit is okay, but clearance might be a bit loose, depending on your printer and material.
• You may want to use sealant or tape for an airtight connection.
• Installation can be a bit tricky — I stacked 3 nuts and used a socket wrench to position them vertically through the access holes. The geometry allows for a small socket to fit, but it's still a confined space.
• I don’t know exactly what nuts I used — I got lucky with a random batch of imperial nuts I had lying around.

Disclaimer: Nutone is a registered trademark of its respective owner. This is a third-party, user-designed part with no official affiliation.