> Thanks for the ideas and the comments, I am greatful for the willingness
> to share knoledge. I had an idea that I could run techscrews into the
> steel box section to attach a block with which to attach the form. The
> sort that drill, and cut their own thread. I have a 1/2 box of them left
> over. The side to side movement might be a bit of a worry. Looks like I
> need to do some more scrounging ( NZ for sourcing material for minimal
> cost) Thanks Don

If you have enough, use 2 lengths side by side but with say 1/2 in or so of ply or scrap separating them. That way you have the stiffness of x section plus something to screw the form stations in. You could glue or bolt the sections together

-mick