Link: https://en.wikipedia.org/wiki/No._14_chair

world's first mass-produced item of furniture.

Thonet's No. 14 comprises six pieces of steam-bent wood, ten screws, and two nuts. The wooden parts were made by heating beechwood slats to 100 °C (212 °F), pressing them into curved cast-iron moulds, and then drying them at around 70 °C (158 °F) for 20 hours.[

Later chairs, as illustrated here, were made of eight pieces of wood. Two diagonal braces were added between the seat and back to strengthen this hard-worked joint.

It has been praised by many designers and architects, including Le Corbusier, who said, "Never was a better and more elegant design and a more precisely crafted and practical item created."

It represents the best example of a design which has been refined to the point where there is no way to improve it.

Seat backs weren't invented for another twenty years.