[taxcontrol]

There is a type of concrete called AAC - Autoclaved Aerated Concrete. It is made by adding powder (aluminum I believe) to the mix and causes the concrete to create air bubbles. This type of concrete naturally floats.

https://www.cement.org/cement-concrete-applications/paving/buildings-structures/concrete-homes/building-systems-for-every-need/autoclaved-aerated-concrete

[Boogieman]

See, this is why I’m not a millionaire. Every time I think I have a good idea, I google it and someone else beat me to it.