The document describes a proposed front door alarm system that does not require electricity. It would use bells to alert the homeowner when the door is opened, and a trap door mechanism that would cause an intruder to fall 10 feet into a hole with an old mattress at the bottom. The total estimated cost is $280.65. Limitations are that the bells may not be loud enough and something could go wrong with the trap door. The original design was kept as proposed.