CamelBack (a cheap one)
Clear Vinyl Tubing (not too thick)
Shirt (maybe a t-shirt or an exercise shirt)
Turkey Baster (or some other manual pump)
What you will do is pound the tubing flat, but not too flat. Line the inside of the shirt with the tubing. Place the tubing where you would want to be cooled off. Use hot glue to glue it down. Cut holes in the CamelBack just smaller than your tubing. Make sure to cut the holes at the bottom. Next attatch the tubing to the CamelBack using glue. Then attach your manual pump to the top of the CamelBack. Fill the CamelBack with cold water and some ice. Dont fill past the pump though. Then put the shirt and CamelBack on and pump away. Based on my research this should work. Unfortunately I haven't tried it so please if you ruin your CamelBack, don't blame me. Keep a look out for the step by step of this soon, and check out some of my other instructables. If you have questions or if you make one yourself put them in the comments below.