I made a little prototype for testing the concept of the PCB build 90° angles for getting adjustable heights to support larger plants that still grow in height.

I used M5 screws to test as I couldn't find my set of smaller rods. Which brings me to mention, you can totally use threaded rods instead of standard metal rods if they are harder to buy where you live. Usually threaded rods are available absolutely everywhere.

I think If I add a second set of fused holders it could work nicely. I didn't make holes for the horizontal rods as I did in my rendering because in this way I can have identical boards to form the angle instead of needing two distinct board design.

Here are a few pictures: