My newest project is making pots from Portland, peat moss and perlite, or sometimes sand. They resemble the garden troughs, originally cement boxes used on farms to water the animals.
In the early 20th century, gardeners bought them up cheap as farmers upgraded and automated their farms. Then of course they became valuable collectibles. The problem is, they are very heavy. Hypertufa looks like the original troughs, but is lighter.
My early and very informal market research tells me they are deeply interesting to serious gardeners and small boys.