To add to the several good solutions that have already been posted. If you created the concentric shapes with scale tool, then you could use that same method but wait to scale the bottom until after the walls are made. Start with the two outer rings that form the lip, push/pull the center to create vertical walls, then scale the bottom down to whatever size you want.
One more option is to use Sandbox toolbar:
Thank you. So simple - I really should have thought of that!
Thanks - I’ll give this a try. I’m feeling spoilt for choice at the moment!
My previous explanations are probably at fault here. If you look at A in my model the sloping wall (formed by the various methods suggested) will be steepest at the 12 o’ clock position & shallowest at the 3 o’ clock position. That is to say, it is not constant around the perimeter of the tray - it will continually vary between these two extremes dependent on position (& thus couldn’t be generated by Follow Me).
With regards the thickness of the material my intention is that it should be uniform, but because my modelling has been focused on defining a surface rather than a solid I have perhaps overlooked some important aspects of the task because my assumption has been that I can simply create an offset once the surface is fully detailed.
That was indeed the part that was missing. @kirill200777’s method would likely be the best start.
Thank you