Make a big igloo in 3 hours using a snowblower, some trash cans and a tarp.
Step 1: Make a Pile of Trash Cans
get about 5 trash cans with lids together and tie a loop of rope onto a few of the trash cans for easy removal from the igloo
Step 2: Create a Plug for Building the Inside of the Igloo Part 1
Lay the bottom row of cans their side on soft snow, don't pack the base down or it will be too hard to dig out the cans. Put the lids on the cans and have the wider top part of the first can pointing toward the door. You will dig in to find the wide part of this can and pull it out first. The tapered shape will make it pull out easily.
Step 3: Build the Plug Part 2
Pile up more cans, and the upper row needs to have the rope loops accessible so you can pull them out easily.
Cover the cans with one or more tarps, I used a big tarp folded in 4. You can pack down the snow a bit around your pile, but
Step 4: Blow Snow Onto the Plug, Then Start Digging Out the Cans
You need about 18-24 inches of thickness over the whole thing, preferably of light, powderey snow. Heavier, packing snow is not as good , it won't last as long.
Then, dig out the trash can at the bottom.
Step 5: Finish the Igloo
Use a toboggan type sled to carry snow out of the igloo as you dig it out.
Smooth out the walls and ceiling so that any meltwater runs down the walls instead of dripping on you. Put a small chimney hole straight up through the top of the ceiling, this allows CO2 and candle smoke to exit safely.
To gauge wall thickness, put some 18" long sticks thru the walls from the outside, and then dig out the interior till you get to the sticks.
It won't collapse suddenly, but over a matter of days it may slump and eventually cave in. You can use the snowblower to add more snow on top and then dig out the interior more.
Make the center floor area higher - with gutters around the edges to cach meltwater and to get you up into the warmer air.