A few years ago -- I made a copper arbor and planted wisteria in the center base and have it still as a "walkway" into my garden. I used epoxy to join the corners and at the time I'd found a plan on the internet. The one thing to ensure is that you have enough copper on the bottom to sink the arbor deep into the soil. Mine does float just a bit when we get a good deal of rain; but I push it back down -- it's only a few inches but I can tell when it's not level. The wisteria grew up around it and it's beautiful when it's in bloom. I let it wrap around the pipes and since the top was wide with no real center pieces, I used 18 gauge wire across the top until the wisteria was "old enough" to stay there on it's own. I have pics of it -- let me know if you'd like to see it. Connie