Sew a Neck Cooler: "Trekkies, the Stake will Provide These"

This site that sells the polymer granules for neck coolers has helpful dimensions for the number of neck coolers per pound of granules. Watersorb
Here are some instructions for the neck coolers the Lindon Stake Trek Sewing Committee are making:
The bandanas are 22" square.
Fold the bandana diagonally through the center.

Find the center point of the folded edge. It should be about 11" from the edge. Finger press a crease to mark the center.

Fold 1 1/2" along the diagonal fold and mark a 12" area center of the center point of the bandana.

Stitch down this 12" area to make a tube for the water absorbing polymer.

Leave one end open to fill with 1 tsp. of polymer. Stitch end closed after polymer is inserted into the tube.

Here are some links. "Sew Very Useful Neck Cooler"  Click Here.

Water Crystals Scarf--Click Here.