Author's Note: In this igloo: marshmallows, toothpicks, cottonwool (to fill the cracks), candle (wax for fire), and coins.
Igloos are not meant to be made out of marshmallows! Tons of toothpicks and icing hold this one together on a overturned bowl as it simply wouldn't stand on its own. Photographed in real snow!
Here are pictures of different views, steps and material.