You can easily use portals how is necessary. PRTI - WALL - PRTO When wall blocks everything, you've got a "transports particles but not pressure" wall. When wall allows air, you've got a "transports particles one-way with pressure" wall You could also use STOR in some ways to make filter walls.
Your the _________ who asked the same question on another thread, got frustrated when we gave you logical answers you didn't like, made another thread asking the same question, and again got pissed when we gave you the same answers that work for everyone else, but are magically obsolete in your view. Wtf man?