This electric pistol can launch a BB or small nail about 20 feet.  It is equiped with a laser sight and high-capacity ammo clip.
Photos courtesy of Richard Caylor of the Twin Cities Robotics Group.

 

The electronics are salvaged from a single-use camera.
Note that the whole unit is powered by a single AA battery.  But don't be fooled, the circuit builds up 300 volts across the capacitor!!! It can launch BBs about 20 feet and stick small nails into styrofoam.

This project is a bit dangerous.  Even being as careful as possible, I still zapped myself twice while dismantling the camera.  If you promise to be super careful and have adult supervision (especially if you are an adult), then I'll let you see the directions.

If you build one of these, contact me and send photos if possible.  I enjoy hearing about people's projects.  So far I know of dozens of people who have built these coil guns based on my design.  Some have reported greater power by adding more capacitors in parallel.
 

Here are some links I found after I built my electromagnetic BB pistol:

• http://www.coilgun.info/sitemap.htm  Barry's great site loaded with projects and theory.
• http://www.coilgun.com/   Excellent site for theory and directions for making a more powerful gun
• http://www.perpetual.net/kyle/index.asp?Section=engineering
• http://www.darkwater.com/sinster/essays/gauss.html
•  http://www.geocities.com/MotorCity/Garage/4293/coilgun.html
• Donnie James' Coil Gun site.  Good formulas and some videos.
• Lone Ocean's Disposable Camera Coil Gun page.  Has some simple formulas for determining the projectile's velocity.
• Greg Miller even sells a kit of parts for making a camera coil gun.  He's also working on a multi-stage coil gun.