hospital bathing pan
, a stainless bowl, old flower pot. Molds are lined with light weight plastic bags, when you start adding the mix it causes wrinkles/lines, just try to pull up on liner/smooth down any big folds. Real bagged concrete mix probably Sakrete. Stuck small sticks in for holes.
Love your troughs & sedum. What form also?
I read somewhere to mix moss and buttermilk and paint it on pots.