Came across this trellis idea this week. I'm sure there are some Home talkers out there who could build this. I'm hoping my husband will create something on similar lines for our garden, I have a perfect spot - once he's build the garden steps of course!
http://www.urbangardensweb.com/2012/06/03/ga...
That arbor there appears to be made from composite decking type material....molded and cast in to those curves. The I beam like structure will be strong and light weight. Doing that in regular lumber would be a bit a challenge but still doable.