Rib
Standing proud, not cut in.
Self-watering pots
The one you buy first.
A groove run up the wall, which is the oldest trick on a column and works here for the same reason: it catches a line of light down one side and a line of shadow down the other, so a pot in a flat room still has an edge to it.
Four numbers change it completely — how deep it is cut, whether the section is round or a V, whether it runs straight up or twists, and whether it runs up at all.
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