I welded corner plates underneath as a flat base for the casters, made side bars to secure an insertion rubber belt, then drilled and pulled 10mm nutserts into all the holes. I then installed, checked and removed the casters, wire brushed, Acetone'd and applied hammertone paint from a spray can. I'll blind rivet the insertion rubber on top of the cental rail once I can confirm centre (with the wings in situ).
