How to Make a Working Bolt Out of Legos

Construct a bolt out of Legos. The ratio of bolt width to height to length is 1:1.5:3. For every two Lego bumps wide, it must be at least three bumps tall and six bumps long. It must be long and smooth, and without any pieces jutting out of it that will catch as it slides forward and backward. Use smooth-headed Lego Blocks to cover all jutting bumps to create an entirely smooth rectangle with no jagged edges. Beyond these basic requirements, bolts function in a variety of different shapes.

Build a hook for a rubber band on an inner part of the bolt. The hook must be internalized within the bolt, or the outward hook must be situated in such a way that it does not collide with the gun while sliding the bolt. The best way to build a hook is to suspend a thin Lego out of the bolt, run it through the rubber band, and then create a complete loop by closing off the end of the loop with more legos so that the rubber band cannot be pulled off without disassembling the hook.

Create another hook on the gun to connect the bolt with the gun with constant tension.

Create a bolt catch. The bolt catch is an indentation in the gun that the bolt will slide into, thereby locking it in position. Simply create a ledge on the bottom part of the gun that the bolt is resting on. The ledge should be placed at a point where the bolt can pull its rubber band to its highest tension point. Build the ledge by creating a long horizontal column. The column should be about half as long as the bolt. The smaller the column, the more the bolt will jut out of the back of the gun when it is cocked. Longer columns will result in a less noticeable bolt. Leave out one or two Lego pieces near the back of the column. This hole will create a ledge that will allow gravity to pull the front corner of the bolt down into the ledge and lock in, thereby cocking the bolt.

Create a gravity-fed bullet chamber above the bolt while it is in its resting position. When the bolt is pulled back, the hole should be over empty space, allowing the object it contains to drop into the space in front of the bolt. Build the bullet chamber by creating a hole larger than the gun's ammunition.

Push the back end of the bolt downward so that the bolt is horizontal. In the coked position, the bolt will be at a slight angle because its corner will be engaged with the column ledge. When you push it into a horizontal position, the bolt will disengage, allowing the rubber bands to snap the bolt forward and impact the bullet, much like the firing mechanism of a crossbow. The bolt will collide with the ammunition and propel it forward out of the gun.