Ordered up some 30mm x 30mm x 3mm square tube and the same in equal angle.
The square is to make the rails for the axes, I just need to locate a 34mm bi-metal hole saw now to fish mouth the ends of the square tube to fit the round profile of the frame tubes.
The angle will be used with the bearing units already constructed to make the carriages or running bits for the axes.
I think I will be drilling the frame pipes and putting M8 threaded stud through to clamp the rails in place. I have discounted welding as the frame is galvanized.
Now the drill is fixed I can do these things.