I believe there are toys that you can buy specifically for making bricks for snow forts. This seems silly if one owns any plastic food containers. We do. The big one once held Sebastian's placenta. We put snow in it.The placenta container made great big bricks.
We used ice cube trays and other smaller food containers to make battlement details. It worked out nicely.
Bastian liked it.
Aleks snuck off into the house on his own after a bit. He said he never got the opportunity to be in the house alone. When Bastian and I came in, he was playing World of Warcraft.