Cool-Ties are sent to the troops during the hot summer months. They should be made out of 100% cotton fabric. For the safety of our troops, desert camouflage or tan is required for those on the ground, but other masculine colors are appropriate for the ships. The red, white, and blue flag-like prints are especially popular for the ships, but please avoid patterns with an exact representation of the Flag, as this violates the military flag code.
A reliable on-line source for the crystals used to fill the cool-ties is available at this site: http://www.watersorb.com/mainstore.html For cool-ties, order the medium size crystals.
Instructions for the cool-ties are available in the pattern section at the bottom of the page. They should finish to at least 45 inches long, and should have the ends finished by tucking in and seaming, with no loose ends or threads
Further down the page is a link to the patterns which then leads to the cool-tie instructions page.
This is all very apt because I am still awake having been too hot all night to sleep (as well as knitting and reading the latest episode of Shadow Unit - highly recommended reading if you like Criminal Minds on TV).
P.S. On further investigation, the Watersorb website has more detailed instructions for making cool-ties. I have emailed them to ask how much they charge to ship the polymer to the UK, but I have a few cool-ties in the drawer (bought last year on ebay) and so there is no rush.