In my location PVC connectors for kitchen hood ventilation are quite expensive so much cheaper to print it yourself.

There are models:

1. Rectangular 204x60 mm - outer connection
2. Rectangular 220x90 mm - outer connection
3. Circle 125 mm - outer connection
4. Circle 150 mm - out connection

Other Sizes & Notes:

• All connectors have borders inside and bevels (for smooth connection) 
• Connection length: 30 mm
• Total connector length: 62 mm
• Wall thickness: 2.2 mm

• Updated:  Added 2 pins for rectangular connectors to prevent body bending (if you don't, just remove in slicer - see last photo)

   

If you need different sizes or type of connections (including internal connection), please let me know!
 
Don't hesitate to like printed model - it gives me tokens for buying filament :)