I made this adorable little fella using 2 strand crochet cotton (14wraps/cm) and 1.5mm hook. The finished platypus is 3.8cm tall, and super cute! I think he will probably end up attached to my mobile phone. :D
The awesome free pattern is available here on Craftster, courtesy of Beavisfreak. (You may need to register on Craftster to view the pattern, but that only takes a minute :) ). The platypus in the photo in her pattern is considerably larger than my little guy. I did not have any trouble following the pattern exactly to make this tiny, scaled down version though.
Happy Crocheting! :)