This instructabule will tell you how to make a gun, that can literally shoot anything that can go in the barrel, this instructabules is also vary cheep and vary powerful.

* DISCLAIMER:
I am not responsibly for any or a injure, or involvement with the law on your part, so think safety! Be sure to where proper protection and be sure to secure all protection

Step 1: Finding the Right Sise

If you already don't know by other post of air guns, or penumic launchers, a air gun consists of a pvc air tank and a valve that allows the tank to flood the air in to the barrel launching the projectile.

upsides

Having a larger tank allows you to have a more powerful round while having a larger, and thinner barrel allows a more accurate shot, and a larger barrel, allowing more of a variety of things to launch.

down sides

having a large tank adds a lot of weight to the gun and will slow you down, a thinner berral is more likely to break under the pressure of the burst, and a larger barrel could not fire the round if to larg
and a longer barrel will definitely add coast to your maneuverability

For my gun i picked a extra large tank, a medium with barrel and a vary long barrel, my gun is vary power full and fairly accurate.

Step 2: Supplies and Tools

Tools :

skill saw
pvc cleaner
pvc glue
jb weld
screw driver
hammer
drill

Supplies:

pvc schedule 40, =
cap, four straight pices, a elbow, skrew cap and rivit piece all pvc

air vavle
air gauge VARY IMPORTANT
metal ties
air hose
air valve for hose
bike handle, with breaking system
main pvc shutoff valve

Step 3: Puting It Together

When you first start to put the gun together, you will always want to start with the tank figure out what design will fit your firing style, and the sises that fits your needs.

See step one

when you start the tank, always start with the smaller couples then the inside of the tank and then the out side.

The tanks usually, are consisting of a input valve, and a open end that leads to a downsized to a main shut off valve.

First, I suggest drawling a diagram of your gun so you can cut the pieces to the right size, and see if that design if right for you, then
you will need to make sure it is vary clean to help avoid air leeks and such, apply pvc cleaner, first and then a layer of tape, then glue, the tape will expand once under pressure and patch any leaks that are soon to happen this step is vary vital.

Glue the barrel and the down size pvc piece last so you can make sure that the tank is air tight, and check for other fixabul flaws.

The trigger system is up to you, because you need to make the trigger to fit your guns style, as mine is on the outside and vary bottom, this allows me to git a better grip of the heavy gun.