For my final assignment I wanted to cast a wall with possible places for mos to grow. By studying the growth of the mos on rocks I found out that the mos needed a concave place with a coarser structure. As I wanted the wall to be smooth I had to make inward curved areas with a more rough structure.
I used the casting technique of prepacked aggregate casting. Prepared with a flat box with thick paper forms witch I filled to half with sand and the other half with 4 mm aggregate. Then I casted with a cement slurry (1 part cement 3/4 parts water). After 30 minutes I took out the paper forms.