If you don't have a bowl with a perfectly round bottom, place cotton on the bottom of a flat-bottomed bowl, then cover with plastic wrap to create a perfectly round work surface for the igloo.
Resources: Paper clay by Creative Paperclay Co.
Clay Polar Bears and Igloo
Your kids can create their own arctic tundra, complete with cute creatures, using child-friendly paper clay. TV crafter Kristin St. Clair from "The Martha Stewart Show" shares the how-to.
The Martha Stewart Show, January 2012
http://www.marthastewart.com/874968/clay-polar-bears-and-igloo
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