I've got a 25' megatree. Last year I used a base ring of 1" PVC. While I was able to bend it into a circle by hand, I found it to be too floppy. The strings pulled too hard on it and it would warp and bend freely as the wind blew. So I want a stronger one that won't warp on the vertical orientation. But I need a material that I'm able to bend into a ring without any specialized forming tools. The circumference is 40' so if I'm doing my math right, that would be about 12.75' in diameter. I'm thinking steel, but open to ideas.

I've heard about using trampoline frames for this, but I've been striking out in local craigslist listings.

So now I'm looking for other ideas.