The final product (if constructed properly) will rival many high-end airbrushes, for about 1/3 of the price.
Step 1: Parts List
All parts are listed here.
Note: All of the parts have the same thread pattern, so make sure of this when constructing your own airbrush.
Step 2: Modifying The Pneumatic Tubing
2 pieces of pneumatic tubing (one at 4" and one at 4.5")
For the tapered piece (part #3)
Heat up the middle of the tube evenly (don't heat it until you see bubbles- this means you have ruined that section).
Then slowly pull on either end, and the tube should stretch.
Don't let go yet! Keep your hands on either side until it has cooled (otherwise it will deform) (blow on it to cool it faster)
Cut the tubing in half, and set those aside for now.
For the angled piece (part #12)
Evenly heat the tubing 1.5" from the end (it doesn't matter which side at this point)
Bend the tubing at a 135* angle
Do the same for the other side, and make sure it looks like the picture (if it doesn't look like the picture, it won't work)