I mentioned up thread somewhere that I would build an arch trellis from a cattle planel. Greeneyes wanted me to post pictures when I did, so I just sent her the link to the Texas Preppers video of grow arches.
Well, since I don't move too fast, mine was an arched trellis for a couple of months... until it started getting cold. I think after our first light freeze, I decided I better get hopping, and finish it as a greenhouse.
My friend down the street has an arched trellis from a cattle panel..The "frame is a little over four feet in width, so the arch is really nice and high.
My Mom's neighbor takes two boards, and attaches to both sides of a cattle panel, then bends them to get a sharp angle for square trellises for roses..He prefers square to arched..I prefer what's easiest which is the arch.