I abandoned the stainless steel baseboard design, mainly because the fabricators were unable to make it without distortion from the heat of welding. At least, they were unable to do so without increasing the thickness and therefore weight and cost too. So, this is plan B which seems to work much better.
Laser cut stainless steel strips with holes for crossbars. By varying the pitch of the holes in front and rear fascias the assembly takes up a curve. So, not being clever enough to calculate said pitch mathematically, I drew it all on CAD and let the software sort it out.
A set of parts for 6ft board is: front fascia, rear fascia, 5 x crossbars, 2 x end crossbars. The crossbars are designed so that some can be fixed flat and others vertical, but their top face/edge will always be the same height. That means the boards will sit flat whichever way they are bolted together. All parts are 3mm stainless. End crossbars not yet
View attachment 76950 used on the test frame photographed.