In this Instructable, I will teach you how to create a very simple blowgun in about two (2) steps, not including the materials listing. Darts will be made in a separate Instructable, as I want to make an Instructable with only two steps other than the materials listing, and darts require some extra work that I don't feel like doing.
You want darts? I was going to make another Instructable, but I got sidetracked and eventually forgot about it entirely. Here's how to make them, though.
There are a few ways, but my favorite would be taking a nail and a page of printer paper to create a cone-type shape. As much as I'd rather make an entire instructable on it, I'll just post it here. (Sorry, no pics...) Take a corner of the paper and hold it to the head of the nail, then simply wrap it tightly around until you make a cone that fits snugly inside the PVC piping.
(Yes, I already know it's impossible to use a blowgun accurately whilst wearing a gas mask like I'm doing.)
Step 1: Stuff You'll Need
You're only going to need about three things, Two if you're skilled at ripping duct tape. (I am not.)
Two feet of PVC, 3/4 inches in diameter. (I don't feel like using the metric system today.)
Tape, preferably the duct kind.
A pocket knife or a pair of scissors for the tape-ripping challenged. (I fall under that category!)
Two hands, though most of my pictures only show one at a time. (The other is holding the camera...)
You can find everything in the above list at Home Depot.
(If you can't find hands at the store, ask the kind man or woman that works there to show you theirs, then take the pocket knife, notice you used hands to grab it and almost cut the person's hands off, apologize, and use the hands that are attached to your arms.)
Step 2: Making the Rear Grip
Take the PVC and put it in front of you. Then, with your left hand, pull the end of the tape to get a reasonable sized piece. (14-16 inches.) With your right hand, cut that piece with the pocket knife. Wrap as you see fit, where you see fit. (Closer to where your mouth is going to go, though...)
Step 3: Making the Foregrip
This has the same process as the last step, but it should go close to the end that the dart goes out of. (If you're lost, go back a step.)
Step 4: Optional Step
Paint it or add colored tape. Do whatever you want to the way it looks, and in truth the grips weren't needed. They're very useful, though...