Nice...
I built 2 hanging racks myself using angle-iron bars. 6ft high, 4ft long, 2ft wide, each cost me about RM100, but last for more than 10 years and still going strong. You might want to cover the wall with a waterproof material so that algae and moss do not grow as a result of the wet conditions when you water.. BTW, IMHO your dendrobium orchid is way overpotted. What is it potted in?