I have a question: why not wood? It's going to be hard to find plans for one that isn't made out of wood, although there is a material I found on a web site that talks about plastic made to look like wood.
Maybe you could use large, round pvc piping for the legs, then smaller piping and elbow joints for the frame. I know that some of the home improvement stores either have remnant pieces or will cut lengths of formica that you could use for a top. I guess there are ways, but it would take some searching around on the internet for more ideas.
My husband and I put mine together in a day (for my birthday) several years ago. We used scrap pressure treated lumber and dog-ear fence slats. It still works great.