150mm vent cover ducting mouth?

thingiverse

I made some modifications to allow printing on v3, then remixed it from another air vent but can't tag the other one yet. I added more material and checked that they're not floating above the bed before printing. I shortened the design, then created a flap for a one-way anti-back draught system. I'm thinking of adding a spring to hold the flaps closed when the fan is off. Any comments or job offers are welcome - be gentle since I'm new to this!