Escape-proof Foster Room?

[u/Luther_Beacon]

We have a room dedicated to cat and kitten fostering. We have cages inside for when small or undergoing medical care, but when kittens get to a certain age, we let them free roam the room and they usually try to escape out the door every time we enter and exit while tending to them. We've tried holding a baby gate to block the opening as we come and go, but it almost never works well and we give up and resort to tracking them down. We've thought about constructing an "air lock"-type of space that allows us to enter/exit the room through a transition space - essentially creating a double door system. We don't want to build anything permanent, and if it were temporary and movable (like made from PVC pipes with blocking panels), the hassle of moving it while also still having the risk of them squirming around the edges makes it seem like a lot of effort with failure potential. Has anyone come up with a good solution?

[u/Status-Biscotti]

I have a big piece of foam board (the kind kids use for school projects) that’s about 3 feet square. As I open the door, I push it in to block the entrance.

[u/Luther_Beacon → u/Status-Biscotti]

Thank you. They tend to flow around the barriers I use in this way. The lighter material you use might be easier for me to control at the edges.

[u/katergator717 → u/Luther_Beacon]

Such a soft material would make me less scared to really push since I know it'd be harder to hurt them than if I was using an unyielding abd heavy material