This shows a cool engineering innovation: canvas-like material that when it is saturated with water will set (over 5+ hours) into hard concrete. In this example a “tent” with regular doors is covered with water and inflated. After setting it hard enough to climb on top of.

The manufacturer’s site has move information.

Related: Concrete pre-fad Houses 1919 and 2007 – Easy to Assembly Off-the-grid Towns – Research on Ancient Roman Concrete Will Allow the Creation of More Durable and Environmentally Friendly Concrete – UW- Madison Wins 4th Concrete Canoe Competition