We love these! They are just the right finishing touch to our fabric-covered bulletin board. We first saw this idea on Daily-Craft and thought it was a brilliant project! Her tutorial is really easy to follow, with great step-by-step pictures. Basically, all you need is a button-covering kit (size 20), fabric, thumb tacks, pliers or scissors, and some hot glue.
First, cut your fabric into a circle about the size of a quarter (or just use the guide that comes with the kit). Then detach the little metal loops off of the backs of the buttons using your pliers or scissors. Following the instructions that come with your button kit, cover a button with the fabric, then put a dab of hot glue on the back and attach the thumb tack.
Ta-da! You now have a fabric-covered thumb tack!