where do you get those grow chambers??

[Zandor]

Fence post are 4x4 (actual size is 3 5/8 x3 5/8)
home deopt has mail box post that 5x5 (4 3/4x4 3/4)
you get a 5 foot section for $20.00 (after cut down)
also some 4x4 pieces and 1 end cap

And Lowed sells PVC fence posts that are just under 5"x5"x100" cost is about 20 bucks plus the gule (5 bucks a tube) and end caps (4 bucks each). They are perfect for 3 3/4" net pots and growing SOG or even screen of green method. You can use bar sink traps as the drain too. Very easy to install.

HD around here needs to special order that size PVC post but Lowes stocks it.