How to Build a LEGO Gumgun

Construct the handle of the gun using simple LEGO bricks in an interlocking pattern for structural integrity. Build the handle to be comfortable to the user's hand. The handle can be slanted, similar to the handles of real guns; however, some builders find a simple vertical column to be sufficient.

Build the basic body and barrel of the gun using LEGO Technic beams and platform pieces as the bottom. Build the body centered above the handle, as this is where the firing mechanism will be located. Construct the barrel to project forward from the handle and body of the gun. Make sure that the barrel and body pieces have a contiguous chamber or corridor that is 2 stubs wide. This is the space where you will load and launch the rubber bands. Add more Technic beams on top of the others to give the barrel some height, and build a stub piece at the front that will act as a hook for the loaded rubber bands.

Construct the trigger mechanism on the side of the barrel just forward of the handle. LEGO Technic beams contain modular holes for mounting the LEGO Technic axles and dowels. Mount a small v-shaped right angle piece on the side for use as a trigger; this piece should therefore include a rubber band to hold the trigger in the forward position when not being fired. You can use the trigger piece to rotate a separately mounted Technic "star" piece -- a piece with three or four intersecting beams which you can mount to a dowel to access the gear mechanism.

Build the gear mechanism. The configuration of gears will depend on the size and types of gears available to the builder, as well as the configuration of the trigger and star piece. When in operation, the gears will be under constant tension, relieved by occasional slight rotations, triggered by the star-shaped piece. You should only mount one gear piece inside of the barrel -- the piece to which the rubber bands will hook. Mount the remaining gears for the reduction mechanism on the side of the barrel opposite the trigger mechanism. Experiment with the gear ratios until the firing gear only moves a slight distance with each trigger pull.

Add any finishing touches, or experiment and modify the gun to look and work as desired. Some extra features that builders may wish to add include a safety mechanism, aiming sights, a forward handgrip, an extended stock, a bipod, a light or laser aiming device, an extended clip and smooth parts for a more appealing exterior appearance. To load the gun, hook each rubber band at the front of the barrel and pull it backwards, hooking the other end over the firing gear mechanism. Manipulate the trigger and rotate the star piece by hand to wind the gear backwards in increments, allowing you to load multiple shots for successive firing. You can load up to 3 rubber bands for each individual shot, up to a maximum of about 20 rubber bands total.