Looks similar to mass's setup or how I would imagine Exo's looks like from the outside. My only recommendation would be to have separate ducts for the humidifier's output and the AC's. The way you have it, there's going to be a whole lot of condensation in the tube after the humidifier because that duct is going to be very cold from the AC's output. You will probably get water collection in the tube, which may flow back into the AC and that's obviously no good. Even not given that, when there's a lot of condensation in there or even a collected puddle, the AC coming on will blow a lot of water out, which will splash water around and make a mess. I understand you want the air cool air and humid air to be mixed before entering the chamber, but perhaps rethink the design. I guess, in all technicality, you could have the AC's duct be U-shaped, and have the humidifier come in at the bottom of the U so any condensation and water collection ends up just running back into the humidifier. I'd use PVC for that, of course. Just a couple ideas.