So, exams are finally over and I've had time to get playing with something again. Some friends bought me a NERF Vulcan for my birthday (cheers!) and of course I had to mod it up. The gun itself is now running off a 3-cell lipo pack, which about doubles the rate of fire, and has three ammo belts chained together to give 74 rounds in one continuous burst of fire.
I then hooked up an Arduino and servo motor to a series of cabletied pencils, which can pull the trigger on command. The Arduino and a USB webcam then connect to a laptop which is running motion and a small python script which interfaces to the Arduino and plays sound clips from Portal turrets when motion is detected/no longer detected.
The whole thing works very nicely, shooting down anyone who walks into my room with a rapid burst of darts, and terrifying them with the portal turret sounds.
Check out flickr for more photos!