This is a simple cheap way to make a device to shoot a long arrow or lightweight spear using very simple easy to find items.
Step 1: Expedient Long Arrow/light Spear Shooter
Gather materials: short pvc pipe piece, latex tubing, 550 paracord, the kind of tape that sticks only to itself, used to repair hoses (optional), two small zip ties. First step is to remove the inner strands from a section of 550 cord, about 3 or 4 feet worth, cut a 1 meter length of latex tubing in half (can be a little shorter), the hardware store where I am in Guyana had two thicknesses of tubing, I bought the strongest. Using the 550 cord outer casing to wrap around the tubing and pvc as shown in pictures, the reason I use 550 cord outer casing is because it will wrap around the tubing flat, when done tie off tightly then wrap that area thoroughly with the black tape that sticks to itself. Cut a short piece of 550 cord with inner strands still intact, put a knot on each side and force into ends of cut latex tubing as shown making sure to leave plenty of area to secure zip ties around tubing blocking knots from pulling through, cut two short 550 outer casing pieces to pass the zip ties through so they will not tear into the tubing. I shot some Amerindian arrows through this one that were about 6 feet in length, it shoots pretty good but would definitely need to practice with it to actually take wild game for survival or self defense with it.