I am trying to build a box that can dry 3D printed filament using a fan and a heating element. This box simultaneously needs to do as good a job as possible keeping the humid air outside the box from getting in.

As I understand it the thought is that when heated the hygroscopic filament releases its water into the air. If I put wet filament in said box and the water released from the filament there would be a build up of steam/condensation in the box.

Ideally I would like to get that out of the box.

I saw one designer (7:02 timestamp) add a simple flexible ring to the top for "steam release" and I really dont quite understand how that design of a steam release is supposed to help. It feels like it might be better to get a proper steam release valve like these replacement steam release float valves to release the steam.

But what I am really unsure about is if this would work. Ideally my little plastic box is not going to be anywhere near the pressure of the pressure cooker. Sure the heating is going to increase the pressure a bit but not that substantially.

I also wonder if the linked designers design for a steam release valve also relies on that bottom hole for what they call "convection flow." It seems to just be an intake valve and given I expect the air outside the box to be more humid than the air inside the box I dont get how having a bottom hole is useful given there would already be a fan circulating air.