Non-curved model that can be made from a single piece of plywood:
https://store.bigguyinatinyhouse.com/products/flat-folding-c...
Yup, that wins in simplicity, but a deckchair is almost as simple, and is a lot more comfortable
This should be the top response tbh.
This looks impossibly uncomfortable though. The backrest looks like it's pushing you off the seat and the chairs legs look like they'd pin in your own. No thanks!!