This is a shelf system I made for my wife to stack her sourdough proofing baskets while being used in the fridge. They are designed so that you can stack as many as you like within reason, I probably wouldn't go any higher than 5 or 6 with dough in them.

For reference a base with a top is 14cm tall (5 1/2 inches), 2 bases stacked with a top as pictured is 27cm tall (10 5/8 inches). Each additional base is 13cm (5 1/8 inches).

Printing recommendations:
Due to the needed pins to keep things together make sure your settings are providing a good bond between layers. I would recommend PETG, but have had some test success with PLA being strong enough. The shelves and base you can print almost however you like, I printed mine at .15 as I like nice detail, but .20 should be fine too.
For the pins I recommend printing them at .15. If they are too loose when pushed all the way in, then just scale them up a touch until they are snug. Mine are fine at designed specs, but I know this can vary a tad by printer.

They are specifically designed for the oval baskets here:
https://rosehillsourdough.com/product/proofing-basket/