I was told that I couldn't buy a BB gun, so instead I made my own version of a railgun that fires 320 Joules in a split second. I was able to pierce my garage door, but I had the switch blow up on me so I'm waiting to install the new high voltage switch.

WARNING THIS IS NOT LIKE A BB GUN.

Used components from old computers and random parts that I found in a voltage converter. So it took me about $30 to make.

But if you don't have everything then it will be more like $150 ($100 worth of capacitors)

Step 1: Material and Guide

Use the Schematic to build the Voltage converter.
You can find the same copy online:
http://www.anothercoilgunsite.com/img-schematic-boost-b.gif
I added a few things to the diagram to make an extra light to show how much the capacitor is charged.
This is the charger, you will need to make the switch using a high voltage transistor or a high voltage switch like the one in the picture.

Step 2: Build

Solder all of the connections in place using the schematics.
Changed out the high voltage transistor with high voltage switched (similar to a solenoid used for a door bell
Changed the resistors to make sure that your peaks and waves for the electrical pulses are at the right rate.
This will determine how much voltage you produce.

Make sure you set one side of the board for high voltage since you don't want any high voltage connections coming in contact with low voltage.

Step 3: Capacitor Bank

Ring up as many capacitors you want in parallel.

I glued 40 capacitors to a piece of wood and strung them up in parallel. Make sure that you use a thick piece of wire to hook them up so the electricity can travel faster. I also added a few resistors and a high voltage diode connecting the positive and negative end to make sure that the voltage wont backfire or arch. If it did then the capacitor bank will blow up. That is why I used 10 layers of duck tape and wood to hold the capacitor bank.

I made a 20 set capacitor bank, but it was not powerful enough.