While I've always liked the original Mario set of coasters, the SNES game lends it's self more to these sorts sets. So I have some bias as to which ones I like more, lol. I plan to make the dark brown block and the music note one as well after speaking to people about the coasters to others at Magfest.
Not visible in the pictures here is the fact that the backs are covered with black felt to help keep the yarn from curling, and stabilize the feel of the coasters when in use.
Time: 45 mins per coasters
Materials: Yarn, thread, felt.