Good for ages 3 and up.
Get the instructions here:
http://www.education.com/activity/article/homemade_igloo/?cid=50.20
Play at home mom 3 also has an ice cube igloo using square ice cubes. She then re-purposes them to draw with and use in the bath.
Get the instructions here:
http://playathomemom3.blogspot.com/2012/03/igloo.html
Making merry memories uses sugar cubes to make an igloo. To give it a snowy texture she sprinkles it with sugar icing.
Get the instructions here:
http://makingmerrymemories.blogspot.com/2011/03/sugar-cube-igloo.html
Campfire marshmallows uses mini marshmallows to make igloos and larger ones to make snowmen.
Get the instructions here:
http://www.campfiremarshmallows.com/frosted-igloo-with-snowman/