Beth Skwarecki's Science & Miscellanea blog will tell you how, with very detailed parts list and instructions. There is even a link to tell you how to use them after you make them. If I had any wood working skills and tools of my own, I would start making these immediately. Especially, since I have wool comb envy in a very bad way. (hint, hint)
I will try to produce something of my own for my next blog post, but no promises.