I recently bought a plastic pair from The Loopy Ewe
. They were inexpensive and that's what I was looking for right now.
You can also get some made of Sintra by Fiber Trends
or wood ones. Leggy Creations
sells hand embellished wood ones and Chappy's Fiber Arts and Crafts
sells wood ones with cut out designs on the top via Ebay. You can also find wood ones at The Loopy Ewe and Scout's Swag although they might be made by Chappy's also.
These are my results of an extensive search. I never did find a good pattern so that is why I ended up buying some. I figure it's probably $19 well spent.
You could buy one pair and then adjust sizes accordingly to make your own.