This is such a great idea, I've been pricing puppy pen prices on Ebay and at Petbarn, then when we were at Bunnings on Saturday I remembered about this - sure enough in the outdoor area they had lots of these compost cages.... we picked up two for substantially less than the cost of the cheapest pen I could find....
Thanks for this suggestion, we may even go back for a 3rd once we get it all set up