- The interior galleries have a roof pitched at 45 degrees which should eliminate the need for supports (there is one small area near the opening where I plan to use them but these should be easy to remove - see the pics).
- There is a divider to segment the fan flow so each set of ducts will (theoretically) get half of the air flow from the fan.
- There is a notch where some fans have a tab which can otherwise interfere it sitting fully in the duct.
- Mounting screw holes are elongated to allow some vertical adjustment.
- There are some other minor changes to reduce the need for supports designed into the model as well.
If this works out at least as well as the duct I was using, I will post it up on thingiverse.