We have a 3 metre balcony edge, of which a steel planter box runs three quarters of the length. We do not want to screw or permanently fix the planter box to the edge but are looking at stabilising it. We were thinking of building a H support with brackets on the inside of the balcony to stabilise. With a 5-6 inch wooden ledge on top of the brackets on the inside of the balcony. Lastly, on one end, to fill the last third of the balcony edge a wooden top that goes 5-6 inches either side of the planter box.
Any thoughts on materials or design would be helpful before we proceed.