There was a Charles Bronson movie where he made a blowgun from scratch, though not as slick-looking as the one jimlay shows in the pics. In case anyone wants to see how it was done the movie the title was, Assassination (1987). In the movie Charles Bronson was trying to protect the President's wife, played by Jill Ireland, while assassins were trying to kill her.
So, they wind up in a hotel room and Charles is unarmed. He makes a blowgun from scratch and winds up using it to take out the assassins. Now, I doubt the blowgun shines in the area of taking out assassins. But I can tell you from experience that it is possible to make a blowgun from scratch using readily available materials and it doesn't take long. Yes, after I saw that movie as a kid my brother and I just had to go try it. What we made would kill a squirrel with no problem. I'll do my best to explain how to make one. But if you could watch that part of the movie it would be better, I think.
Get a pipe, about 1/2" in diameter works fine, though any size is fine so long as it's not so large around that you can't propel your dart down it.
Next, get a wood screw, adhesive tape, and a piece of notebook paper. Roll the paper into a funnel. (small at one end and large at the other) Put the screw in the small end of the funnel with the point facing forward, out of the small end of the funnel. Tighten the funnel until it is snug around the wood screw with the screw-head inside the paper funnel. Tape the funnel in place at the seam so it doesn't come apart. Then tape the area where the screw threads come out the paper funnel, making sure to get tape on both the screw threads and the paper funnel itself.
Now put the screw end of the funnel into the pipe until the larger part of the funnel gets too big to insert further. Cut the paper funnel at the point where it gets too big to fit into the pipe. At this point you should have a "dart" that fits snugly, but not too snugly, into the pipe.
Lastly, set up a target. Put the dart into the pipe with the screw facing forward. Take a deep breath. Blow as hard as you can. The dart should nail the target.
Well, if you're looking to make one of these I wish you luck and please report your results.
Sorry if my description of making one of these is lacking. I'll do my best to clear up any questions if I see anyone asking in this thread.