Nice cheap pots from Home Depot (USA)
I was browsing Home Depot's pots and found a box labeled Pennington Vertical Garden Kit. I sealed the drain holes with a metal disk and RTV bathtub caulk and put about an inch of gravel in the bottom. Top to bottom: h. Curtisii, obovata, and pubicalyx are 4 x 4 x 5 inch deep square plastic pots that just fit. Curtisii seems to be growing away from the light.
I have only had them since late November last year and they are all growing faster than I expected.