That was my though too, those thin stands may look sleek but they don't really do anything in terms of heat transfer. If anything it'd be worse since now the machine has nothing to transfer the heat to.

Aluminium is a much better heat conductor than steel.

I fee like I've seen a lot of thick steel plates around the right size sitting around in old workshops. You could probably find something cheaply from a scrap dealer.

Thick aluminum or copper seems more rare, I don't know if it's commonly produced.

Solid aluminum is not hard to come by. You can probably just walk into your kitchen and pick up a frying pan.