To make a snow fort, all you really need is a plastic bucket or tray (you could use sand pails or even banana bread pans!).

Spray those with cooking spray.

Pack the snow in.

If it's powdery snow, spray some water into the container once the snow is in. That will help it harden.

Dump the blocks out and start building!

You can make a four-walled castle, or fort, or go crazy and make an igloo! (Igloo blocks are laid down in circles that get smaller as you go. Slope the blocks so they incline toward the center. Use smaller and fewer blocks as you get closer to the top).