Construction

I bought two big sheets of black, 1/8^th inch thick ABS plastic, and a 2.5 inch diameter black ABS plastic pipe for the rounded parts.  A few other little plastic bits, including the pistol grip, were salvaged from old Airsoft guns. I cut the plastic with a hack saw, finished the edges with a file, and glued the parts together with ABS cement.

This was the most tedious part of the project, since many pieces had to be remade over and over again.  With projects like this, many things have to be done wrong before they can be done right.  And the little black flecks generated from sawing ABS plastic get everywhere- in your hair, in your nose, in your food, and all over your home, no matter how hard you try to keep it clean.

Capacitor Bank

The capacitors are connected in parallel by two bus bars.  A plastic support structure (essentially an upside-down T-Beam) helps the bus bars hold the capacitors rigidly together.  The whole thing is cased in ABS pipe segments, and holes are drilled in the top of the gun that are just big enough to let a screwdriver down inside to unscrew the capacitors should they need to be replaced.

The coil was wound tightly and carefully around the barrel between two hand-made plastic washers and a plastic loading breech.  In between each coil layer is a single layer of clear packing tape to help the windings stay together.  Winding the coil neatly is important- asymmetrical or off-axis turns of wire will reduce the efficiency of the coil.    A layer of clear heatshrink tubing was fitted around the coil exterior to protect the windings from scratches.  Lastly, I chopped down a cheapo laser pen and mounted it to the front of the barrel for targeting.

The trigger was the most difficult part to construct.  It swivels smoothly between two screen door bearings which barely fit into the gun, and is pulled forward by a coil spring.  Several different springs had to be cut and tested before I got one to move the trigger consistently with the right pull force.  Also the little metal wire contacts on each side of the trigger had to connect nicely with the contacts inside the gun body to power the charging circuit when released and to hit the SCR trigger when pulled back.

Assembled Gun Trigger

Loading Mechanism

The bolt-action loading mechanism is a standard spring-loaded cabinet door latch that clicks back and forth nicely and holds the projectile with a small magnet.  The latch had to be filed down and painted black to fit with the rest of the gun, then placed to put the projectile into the optimal position when forward.  I also attached a plastic lever to the top to allow easy single-handed bolt operation.

Loading Mechanism

One of the last things to do was routing all the wires through the gun to connect everything together.  This was an immense task, and took much planning and many drawings to accomplish neatly.  I used a standard 9-pin serial connector to pass all of the wires onto the charging circuit board, and I made little plastic brackets within the gun body to hold the wires neatly in place.  I was also careful to make sure every external conductor had at least two layers of insulation, to improve the safety of the design.

Forward Electronics Compartment