Step 4: Extra info
The plastic tips of a shoelace makes the easiest dart, but do not throw away the rest of the shoelace... with a little duct tape, you can create a vast arsenal of darts from a single shoelace. Cut the remaining shoelace into 1.5 inch segments (or just a bit longer than the pin to be used). Take a short piece of duct tape - about half an inch wide and a couple inches long (or roughly 1.5 x 5 cm). Wrap the duct tape tightly around one end of the shoelace segment. Trim the duct tape tip to about half the length of the pin. Follow step 1 to fluff out the shoelace and then insert the pin through the duct tape tip.
Ideally, the dart should fit snug in the tube. Too loose and the dart will not shoot with much velocity. Too tight and you'll go blue in the face trying to blow the dart out. A nice snug fit will ensure the best performance of your simple blow gun. Enjoy!