This thread reminds me of the old saying. Idle hands are the Devils playground. Maahahaha!
I spent the 4th building lawn dart like projectiles for my spud gun. Took a 1 1/2" wood dowel 2"long and adapted an arrow to the back end of it. Worked pretty good. Had to use a little wodding to get it to fit tight enough. We would shoot it almost straight up and try to see who could get closest to the target. It is best to have a large area because it can go way off.