For this assignment I tried to cast in a medium with higher viscosity than water. I found that tapestry glue might shape the concrete without any other formwork. The glue mixture was made according to the instructions for putting up wallpaper, so it was quite thick. The concrete would sink slowly, I poured it in different parts of the container to see if this would create a variety of shapes. Some of it would just sink to the bottom, but when I poured the concrete slower, the lesser weight would make it float in the glue mixture.
Top view of the glue and the non cured concrete
One of the shapes