Gas impermeable mesh tiles

[TheScaryOne]

I would like to be able to collect liquids from a room passively without having gases pass, ie keeping a small room flooded with CO2 for slicksters and collecting it via gravity drain in a lower room without letting CO2 spill through. 

Should use raw or refined metal and plastic and not return plastic on deconstruct. 

[Coolthulhu]

You can do it already. Build an L-shaped tunnel at the bottom, so that anything that wants to get in or out has to get through the oil.

[AlexRou]

I don't think there is any material in real life that allows liquids through but not gases. I feel like this is a little too fantasy, especially when you can use a liquid lock.

[AileTheAlien]

Just build a liquid pump at the bottom. It won't pump air into pipes.