That only lets solids in? Sounds too much like moving solids. How, exactly, would it allow solids in?
1. Allowing solids to be drawn in it when the wall is drawn as a hollowed, completed shape?
2. Or moving solids? Maybe a Wall that allows solids to be pushed in by piston?
Perhaps allow solids to be drawn in it (like you can draw them in ehole, conductor wall, etc.), but block other particles?
Take both numbers in consideration. Imagine the type of reactor one can make that allows nuclear fusion to be made by a piston pushing a solid through the wall. Not only will the solid melt, but all nuclear particles cannot escape and destroy the setting the reactor is built in.
I was thinking some kind of isolation for preserving delicate components that shouldn't usually get blown up by a small air current, or some fray gun. And no, its not moving solids, it's just drawing them inside for them to be protected from non solid dangers or high pressure, that's all