So I sent my husband to the store with a request that he bring back a "big ol ball" of sisal garden twine, followed by an assurance that there was such a thing, and yes, it would be easy to find.
With a ball of sisal garden twine and a size K crochet hook.
dc- double crochet
ss- slip stitch
12 dc in a magic ring ss together
ch 3 (doesn't count as dc) 2dc in each dc around (24 dc) ss tog.
ch 2 *sc in next dc then 2sc in next dc* around. ss together
cut sisal finish off and weave in end.
With scissors, trip all the long stings that stick out (give them a quick shave) for tidiness.
The sisal can be rough on your hands. You have to really work it but it can take a beating. After four, my hands were getting sore, but it wasn't too bad. The coasters will curl up a little at the edge which works great with small galsses and coffee cups. If you are a giant mug drinker (like me) they are perfect sized and the mug of coffee will quickly flatten them out. They're flexible and easy to mold/manipulate because of the sisal.