I use to make these planters of hypertufa, an artificial material that looks like a natural stone. Everybody has it's own hypertufa recipe; I use peat moss, Portland cement and sand in 1:1:1 ratio. Vermiculite or perlite can be added too. The ingredients are then mixed with water. Make sure to wear gloves. Add water bit by bit, squeeze the mass through your fingers, turn and mix until you get not to runny mixture to build up around a plastic mould.
Use different plastic moulds to make the planters on the pictures e.g. empty margarine or ice cream containers. Firstly, form the bottom, then put the mould in the middle and build the hypertufa mixture around it. It is not necessary to look neat. If it is rough it will look more naturally. You can incorporate a nice piece of stone in the planter or make handles.
Do not make lots of hypertufa at once. The next day (usually after 24 hours), when the planters are firm but still workable, you have to scratch them with a nail an brush with a steel brush. If you have made too many planters you may not have time to work them out. Let them dry completely (usually two weeks in summer). The water hole can be made immediately or you can drill one later when the planter is dry.
Plant them with Sempervivums, Sedums, Thymus coccineus and similar plants.