How to Make a Simple Homemade Pen Gun

Updated February 21, 2017

Homemade weapons demonstrate ingenuity and allow the owner avoid buying a mass-produced gun. You can make a simple pen gun that will fire a projectile using a toy gun cap. You will need a few household supplies and a roll of toy gun caps from a hobby store or toy store. If you are a minor, you must have adult supervision because the pen gun uses an explosive to fire the BB pellet

Put a sheet of newspaper on a table. Hold the disposable plastic pen by the front end in your left hand. Hold the pliers in your right hand. Pull off the cap from the back end of the pen with the pliers. Dispose of the cap in the trash.

Hold the disposable plastic pen by the back end in your left hand. Hold the pliers in your right hand. Clamp the jaws of the pliers around the front of the disposable plastic pen. Twist the pliers to separate the front shell from the back shell. Pull the front shell off.

Point the back shell down. Pull the ink cartridge out of the back shell. Remove the spring from the ink cartridge. Put the spring over the point of the nail. Push the spring up to the top of the nail. Insert the nail, point first, into the front shell of the disposable plastic pen.

Put the ink cartridge back into the back shell. Push a cap off the toy cap roll.

Place the cap gun cap against the point of the ink cartridge that is inside the back shell. Place white glue around the rim of the seam of the back shell. Place the front shell onto the back shell. Hold the two shells together until the white glue takes hold. Let the white glue set for an hour.

Go outside. Put on the work gloves and protective eyewear. Put a BB pellet into the hole at the back end of the disposable plastic pen. Aim the pen gun you have made at a tree or rock.

Pull the nail out of the front end of the air gun you have made. Release the nail to explode the toy cap gun and fire the BB pellet.


You can shoot foam pellets rather than metal BBs to lessen the risk of damage to whatever the pen gun is aimed at.


Do not aim a pen gun, or any weapon that shoots a projectile, at a person or pet.

Things You'll Need

  • Newspaper
  • Toy gun cap roll
  • BB pellets
  • Disposable plastic pen
  • Pliers
  • White glue
  • Work gloves
  • Protective eye wear
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About the Author

Marshal M. Rosenthal is a technology maven with more than 15 years of editorial experience. A graduate of Brooks Institute of Photography with a Bachelor of Arts in photographic arts, his editorial work has appeared both domestically as well as internationally in publications such as "Home Theater," "Electronic House," "eGear," "Computer and Video Games" and "Digitrends."