1 ball bulky gauge wool ( I used Knitpicks Wool of the Andes)
5.0mm & 6.0mm crochet hooks
Using smaller hook, make a chain of 30 and join. Chain 1 and SC in each stitch in the round. Keep going in a spiral (meaning don't join to first SC with a slipstitch), continuing for 7 rounds. Switch to larger hook and continue with SC for 3 more rounds. For top edging: Slipstitch into SC, chain 1, slipstitch into next SC, chain 1, continue until you've gone all around the top edge. Fasten off.
Attach wool to bottom edge. Will smaller hook, crochet the slipstitch, chain 1 edging as above. Fasten off and weave loose ends into body of cozy.
Voila! An easy-peasy way to keep your java warm and your palms, burn free. Or I guess you could also use one of those reusable travel mugs.