Before me, various makers built LowRiders using metal struts sold in a couple of brand names, Unistrut and SuperStrut. They have screw holes / slots on one side, smooth and flat on the others (and open of course on the side opposite the screw holes). The motivation seems to have been that it’s a flat, smooth, straight surface long enough for a full-size LowRider made for full-sheet cuts.
My idea was hiding the belt(s) inside the C-shaped struts.
Since a LowRider needs a flat surface to roll on, it seems problematic to have holes on all three sides. But if the holes don’t cover the whole side, you could perhaps target the build so as to make the wheels roll on the smooth part.
I‘d really just build a „normal“ table if you are not sure why you are building it. The build is more complicated and does not necessarily offer an advantage.
One of the reasons I decided to go with metal rail is simply the price. If I use metal struts I will not have to buy 2 sheets of plywood. And good plywood is expensive…
For now I will build temporary table (c24 pine + mdf) and then use it to cut @DougJoseph design torsion box. I still have problems with importing dxf/svg files into FreeCAD, so this will take me some time anyway.
I have found Niedax after all, but will have to wait few weeks for delivery. Thanks @Dreyfus