I appear to have placed more emphasis than I meant to on the “540c” part. The goal of this project would be to replace ALL of the various PowerBook models’ easily damaged parts. For example, I have a 180c whose case was destroyed because the moron who pulled the drive Back In The Day didn’t put all the hinge screws back in, so what I took to be a loose hinge when I bought the thing turned out in fact to be the part of the shell to which the hinge attaches being shredded a little worse every time the thing was touched. Those parts of the case are now completely, and apparently irreparably, destroyed. Other parts like the port cover on the back broke off long before it got to me and are now more or less unobtainium.

At a minimum, a project like this one to produce 3D model files for the few genuinely near-irreplaceable PowerBook case parts, mainly port covers and screen bezels as far as I can see, would seem to be well overdue.

Regarding your other point, the relative ugliness of a 3D-printed part is by no means a constant. If you pay enough money, a suitably equipped shop can produce output that is almost as good as a proper moulded part. (In any case, I am seriously considering having any parts I have made for my own use printed in metal. Brass would look nice and be sturdy. It would admittedly also be fairly heavy, but that doesn't really bother me much.)

For that matter, once the model files are available, it’s a lot less of a stretch to have something fabricated by a less cheap-ass production process, at least for the better-funded among us.