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
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.)