For my daughter's new room I have crocheted a carpet from a kit by FROSTA Design. It has about 70cm diameter and took only a couple of hours to crochet. The hevy weight yarn (rope?) probably looked very easy to crochet with, so my 7-years old daughter asked for some of the yarn and a crochet hook. Once she got hold of it she started crocheting and she is still going strong... it is now at least a 20m long chain :-).