Over the weekend we were running some workshops using the #PewPew Standalone, and I brought the version 4 prototype along to show it to people. I carried it both in my pockets and in a box full of tools, and then it went through a lot of hands, including a couple of kids. This is a great sample of the kind of handling I expect from this device, so it was a nice wear-and-tear test. Unfortunately, the results are not very good.
The 1mm thick acrylic cover is certainly a weak point. The two top corners broke away, and the two bottom ones are already cracked and ready to break as well. Also, the bar on top of the lanyard hole broke off.
I could move the holes further down and maybe a bit towards the center, to have more material there, but I think the whole idea of holding down a 1mm acrylic sheet with self-tapping screws like this is flawed. The top bar is not a problem — I can remove it completely from the top layer. But I think I need to come up with a better way of holding the two layers together (and then have the screws only hold the middle layer, which is 2.5mm and shows no signs of cracking).
Glue is an obvious option, of course, but I'm afraid it could work badly with the fact that the top plate is transparent, resulting in a surface with visible bubbles and/or clouding, which wouldn't be too nice to look at. A particularly interesting option would be to use an acrylic with pre-applied adhesive tape on it — also because then the tape could give me an additional 0.1mm of thickness that I need for the USB port.
Another option would be to forget the laser-cutting, and instead go for injection-molded case. I could then have the whole thing in one piece, with the exact dimensions I need, with proper transparency, and probably much cheaper in bulk as well. Also, rounded edges. Also, I could probably even incorporate the battery holder in the case itself, which would get rid of a tricky assembly step. The problem is that it would be quite expensive in small quantities, as the most expensive part is the mold itself.
Yet another option would be to use thicker top layer, and simply find buttons that would work with it better. I might go on another button-buying spree and see if I find something that would have a body that fits in that 2.5mm space, but has the button itself sticking more than the 2mm of the top layer.