I got bored one day, so I built a bow. And some arrows.
Step 1: Materials
As this is a very simple bow, you really only need a few parts. You're going to need-
(1)- 3 feet of 3/4 in PVC, (2)- A 3/4 in 4-way connector, and (3)- a good bungee cord-- I found a cool adjustable one that can change length up to a max of 4 feet, which is plenty. I would suggest a good-stretching one between 2 1/2 and 3 feet long, possibly shorter. Also, you're probably going to need a saw to cut the PVC, unless you already have two 1 1/2 foot sections lying around.
Step 2: Pre-Assembly
These are the final steps before the final assembly. First, if you haven't already, cut the 3-foot piece of PVC in half. Also, if you've got my bungee cord, adjust it to about 2-3 feet depending on the arrow length. For longer arrows, use a longer bowstring. Finally, if you want to, you can glue the limbs into the joint, but I won't for two reasons.
One, I want mine to be able to collapse, so I can sort of fit it in a backpack. Two, I have a cool idea of something to do with a few more parts on this bow, which may involve taking a limb off, in which case, gluers would be out of luck. I'm going to test my idea, and if it works maybe I'll edit this instructable to include it or make a new one. I'm not saying you cant glue it. You can if you want. It will make the bow more sturdy for sure.
NOTICE-- The duct tape on the PVC in the picture is cause I put a grip on the completed bow before I made this instructable. Just ignore it.
Step 3: Final Assembly
Now it's easy. Just put the ends of the pipes into the opposite sides of the connector, and hook the bungee cord into the open ends of both limbs of the bow. Then you can make some arrows out of wooden dowels or something and go nuts!