I made these as gifts for some friends. I used a 1.5mm crochet hook and the equivalent sized yarn. At 2.4cm (or 3cm including tail) these tiny cats were the perfect size for attaching to a mobile/cellphone or key ring. Although not in the pattern, I also crocheted a length of chain stitches to use as the strap and ran it through the body and secured it at the bottom.
They are so adorably tiny!