I've since added the round section to the table frame. We had a local shop bend the square tube to a radius of 18", then I cut and notched all of the joints to match the 3" round tubular legs. Then hand rolled a frame to match the 18" radius from 1/8" cold rolled bar and welded in the 1/4" hole perf to the inside of the frame. 

 This is the section where the Fan and blowers will be mounted under the wind tube that is later to come.

 After welding the fames I hand brushed the metal with a scotch pad to give the black patina something to bite to. This will be the next step in to process. Then we will add the 1.5" maple ply top and tubes.