Begin by oiling the inside of the larger (exterior) flower pot mold, taking extra care when using a fluted mold.
Oil the outside of the smaller (interior) flower pot mold.
Mix the concrete and fill the larger planter mold with concrete up to about 2 cm (1 in.) from the top. This will stop the concrete from overflowing when you add the smaller mold.
Shake the larger planter mold with the concrete in it to get rid of any air bubbles and to level the surface of the concrete, then press the second, smaller mold into the middle of the larger one. Don’t press it down too far or else the base will be too thin.
Put a weight in the empty, smaller mold to stop it rising. Leave the concrete flower pot to set.
Wait 24 to 48 hours, depending on the size of the pot. Carefully remove the molds and to finish, smooth away any sharp edges with a stone or a file.
This concrete flower pot how-to is excerpted with permission from <a href="http://www.amazon.com/gp/product/1604692820/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1604692820&linkCode=as2&tag=craftfocom-20">"Concrete Garden Projects: Easy & Inexpensive Containers, Furniture, Water Features & More"</a> by Malin Nilsson and published by Timber Press. Images from Camilla Arvidsson.