Every night, at 3 AM, my cat will meow and paw at the bedroom door like a banshee. I tried everything to get him to stop, including the off-the-shelf air sprayers that trigger with motion. Eventually, I decided to build my own. I 3D printed a case and trigger for an air sprayer can, created some electronics with an ESP32 and RF trigger, and wrote my own "motion detection" logic - this time with an ultrasonic sensor,…
Serious question - have you considered just leaving the door open?