I just acquired a lumber rack and i'm about ready to cut it up and weld it together.
I will probably be using my existing Yakima rack rail mounts with 1 1/8" round tubes for mounting. Rack size will be 48"X60"X5 1/2" and the frame will be out of 1 1/4" square tube. I think the floor will be made out of 3/4" EMT riveted to the frame. Not sure yet on what to do for a spare tire mount yet.
I'm also considering getting a set of Rain Gutter Mounts, as well...
Jeep Cherokee XJ Roof Rack Mounts: JcrOffroad, Inc.
Any cool ideas would be great!