Ok, it looks like smallish was the wrong word choice. I hadn't seen the dimensions and it didn't seem like an inch thick in the pictures I saw or in the descriptions I read that said it folds "completely flat." The devil
is in the details. But now we all know why I just read here.

I rounded up
Size:26cm*32cm*1cm 
I did a search and found this interesting thing,
uses thick cold-rated hvac foil tape
to reinforce non-stick aluminum foil,
seems to last more than one
boil/fry/unfold/clean/fold cycle
kfXKqG9mHYc Reusable folding foil Cook Pot WATER TIGHT - Jay West
So, for about $13
(~$10 foil tape lowes/home depot, ~$3 foil)
you could probably make 13 of these

they hold 2-4 cups at least ...
otoh a large aluminum roasting pan can be had $1.09