The frames of my orchid benches are built from treated pines, which will have a life expectancy of 15 years. Yours is much much stronger, life time guarantee assured 🙂
I chose metal frames for the portability and the small visual footprint of the structure.  The most expensive parts are the Elgate/Downee pipe joints, which are infinitely reusable. The whole structure can be deconstructed and repurposed for another location. It is like Mecano to assemble
Benches are filling up nicely  Deflasking this evening and tomorrow to fill out the bottom bench and job done till second lot of repotting in October