You can buy snap clamps of different sizes and lengths here and other places online. Prices are all over the map so if you like to save every penny possible, do some additional research.
http://www.charleysgreenhouse.com/in...productid=1725. The snap clamps makes it easier to vary pipe size. I made one of these frames for myself and it worked great. Hubby also helped me make a king size wood frame and we used pipe for the legs. It's in the garage now, but I'll see if I can dig out the legs to show you how we did it.