Prop the flap open so daylight shows through, feed on the far side, and give it days rather than minutes — a 300 mm tunnel is a corridor a cat has to commit to.
Wall installations ask more of a cat than door ones.
Why it is harder
A flap in a door is a swinging panel. A flap through a wall is a tube the cat cannot see the end of until it is inside.
Prop it open
Tape the flap up at both ends if you have a double-flap installation. A tunnel with daylight at the far end is a passage; a closed one is a box.
Feed on the far side
Not through the tunnel — beyond it, so the route has a destination.
Give it time
Days. Cats that walk through a door flap immediately can take two weeks over a wall tunnel, and pushing them through sets the process back.
Last reviewed 2026-08-17