Just like a cat door, but smaller. Mice which have been brought in by cats as playmates can use mouse doors to leave when they don't want to play anymore, without the cat being able to follow.

The problem is, I'm not sure how to train the mice to lift the flap to get out. I thought maybe if the route was more like a sock they'd be inclined to nuzzle forwards until they came out the other end, but then I couldn't work out how to make that one-way.

Maybe some kind of vacuum tube arrangement?
-- b153b, Jun 24 2019

One-way escape route https://www.amazon.com/-/dp/B0007DHT8Q/
I think this should work. Mind where you point it, though. [b153b, Aug 24 2023]

Mice are vermin. Kill them all.

[-]
-- 8th of 7, Jun 24 2019


Mice are one of the greases in the wheel, don't over or under lubricate any of the greases.

Maybe, a tubular maze that just reduces the indoor outdoor flows. The mouse will have something to ponder on the way out.
-- wjt, Jun 26 2019


When Frisco is done playing with them they don't have a leg to stand on...or run on, or, well...you know...
-- blissmiss, Jun 26 2019


Just use a conical tunnel like a lobster trap entrance. Make it a bit springier, maybe, so it closes down tighter when no mouse is going through it, because mice can squeeze through very small openings.

Or just make a Tesla valve for mice.
-- notexactly, Jul 21 2019


The Tesla valve could lead to a Tesla coil ... nice. Just add a big brass-and-mahogany -and-bakelite We Belong-Dead knife switch and it's perfection (with a side-odour of singed fur).
-- 8th of 7, Jul 21 2019



random, halfbakery