Matt writes –
This project captures a mouse by having a solenoid (electromagnet) drop a bucket over the mouse. The bucket is triggered by the mouse interrupting one of the infrared emitter/detector pairs around the bait. The enclosure that holds the electronics is mounted directly over the bait. Ok, so the “bucket” is actually a semi-clear storage container. The clear container allows a person to see if a mouse was trapped when the container dropped.
More: continued here