At first I didn't think much of these chairs, but the more I look at them—particularly in the video below, where the camera moves around them—I think they're fantastic. Designed by Philippe Starck for Spanish manufacturer Andreu World, the Adela Rex chair is made from just three pieces of plywood.
Archiproducts writes that the chair's three pieces come together "like a puzzle, without fittings, screws or additional materials, making the seat and backrest interlock smoothly through curves and careful details," but in the photos below we can clearly see what I assume are holes for dowels:
I can't investigate further, as at press time the chair was not yet on Andreu World's website; as for Starck's website, I haven't been able to get it to load for the past month—is it just me? Try clicking it.
In any case, this video gives you a better look at the chairs than the stills do, and you can also see the upholstered versions, which look pretty good: