Avoiding Light Leak when venting cabinet

How do you vent both intake and outtake and not have the light leak out?

Will those angled dryer vents work? Or do you have to get a couple elbows together and make some S's?

Trying to figure out the best/cheapest way to do this.

I have a room where i'd like to run 12/12 lights in, but then a 18/6 cabinet in the same room... I'll only work on them during the 12 on hours, but i need the light not to leak from the cabinet at all..

If space is limited, you can use what is called a "darkroom register" which has louvers that prevent light from going through