Edward's suggestion seems like the way to go, a magnet on one side only and a washer on the other. You can reduce the grip and the snapping noise by...
With your space limitations, maybe you can't have an aircraft carrier to land your planes on. A bench-centric shop may suit you better. Shrink the SS...
Snap lock duct should be fine if it is not put under full suction. Screws and rivets may catch tangly stuff and can be a real pain if the duct needs...