I've run across several posts about building igloos with all the snow we are getting this winter in various parts of the country. Cool Tools have reviewed several igloo making tools and resources in the past. Including the documentary on igloo building embedded below.
The Toy Report had a fun post recently about building an igloo as a family project. They ended up using a plastic storage container to shape the blocks as they found the "toy" forms pretty much useless. Their igloo is shown to the left. One item I thought was interesting was that they discovered that they needed someone inside to build the walls stating:
"Do not attempt to get in or out of the igloo or build a doorway until the igloo is complete. One person stays inside to place the blocks, the other makes the blocks."
If you watch the documentary below, that's exactly how the Eskimos built their igloos. Including the last two pieces of the roof that were fitted from the inside out.
[Image: Captured from Toy Report: http://toyreport.org/family-life/building-kids-igloo/]