For me the challenge was to make a tray at home, and so I had to compromise on thickness. My bending rig is two lengths of timber, a vice and two G clamps.
Sometimes I use my jack handle, which is a large diameter aluminium tube.
The easiest way is to build it up in sections, which is how my third tray evolved. Given that the flimsy plastic tray holds the tools reasonably well, 1.2mm, or 1.5mm will do the job for the DIY fabricator.
There's quite a difference in working 1.2mm and 1.5mm, and inevitably some pieces get scrapped, but that's all part of the fun!
