I’ve been seeing this a lot lately: use a laser cutter to make many cuts, allowing the wood to bend where the kerf has been removed. This is also known as a “living hinge” and has been popular, albeit labor intensive, since the advent of tablesaws (or earlier? Post a link). The above Arduino + radio enclosure was made from walnut by Shaun Crampton (via Hackaday) and he also offers a detailed tutorial for making a similar box of your own.
I think the screws look much more noticeable in the photo than in real life. I might have to give alternative joints a try though. That keyed tenon looks like it’d stick out quite a way on a small piece like mine. I wondered about gluing on the end caps and then using a little peg (like on the top) to hold the bendy piece in place. Or, maybe using glued-on magnets to hold the sides down so it’d be easy to remove for maintenance.