The Infrared Nerf Autocannon is a Non-Lethal Guard Dog

 - Sep 5, 2010
References: & engadget
If you've ever wanted a high-tech security system to guard your home and worried about tripping the sensors yourself, the infrared Nerf autocannon is a system that will quell those fears. It gives you an auto-targeting turret that can guard your home with the best of them, with no chance of anyone getting hurt.

To make the infrared Nerf autocannon, Rick Prescott customized a Nerf dart gun with cool toys like an infrared tracker, motor, and battery pack; he also made the gun capable of firing semiautomatic and automatic rounds. I think it's the most fun security system I've seen.