Custom watch crystal / Plexiglass

I looked into custom crystals sapphire/mineral crystals at one point, and it is a pain to have done by someone else. I simply wanted a slightly oddly detailed ROUND one and it was horrible. I considered grinding one on my own on the lathe, but that was for a round one (I ended up just polishing the crap out of the old one :/).

Plexiglass is actually quite a bit easier, and what I would suggest for you. IF you can model it up in CAD (which I suggest test-fitting with a 3d printer), there are a lot of sites like PCBWay/Xometry/etc that will make something out of plexy for you. You might have to polish it yourself, but it should be easy enough (you can polish from completely unable to see through to crystal clear in like 45 mins).

Probably? A 3d scanner would possibly do a half decent job of a first pass, but I would bet there is going to be quite a few adjustments in CAD over time to get it just right. But any CNC machine could make one out of plexiglas, and there are plenty of low volume manufacturers online.

And yes, they will likely be rough-machined unless you spec them as polished, but polishing would be really easy to do yourself.

IF it were me, I'd pick up a 3d printer (maybe a resin printer for the accuracy? There are actually clear 3d resins...) and get to trying to design one that fits right, and cycle through prints until you get one that matches perfectly. Then, either clear-resin print them (though they tend to be softer plastics?) or have it CNC manufactured by PCBWay/etc.

I have a modicum of experience here from the speculation department. Namely that I have a 1655 omega equinoxe on the bench with no bezel or crystal.

I have also been working with the 1340 micro motors. I was able to have a motor scanned by structured light. Also a 552 base plate was scanned. The motor was a bit small, and the sales demo person did not include the file. I did get the stl for the watch plate.

Additionally I downloaded the polycam app. My phone which is a mini13 does not have the lidar sensor. So I had to use the photo matching. Which is too coarse for these small objects. The program is also subscription based. Which does not work well with my eclectic nature of jumping around a lot of different projects, where I can let things slide, sometime for decades (or even half centuries.)

These systems seem to be targeted more around automotive size parts. Something in the 5 to 10 inch range or larger.

A lot of this is based on open source code, so there are a lot of options for making one's own scanner, although it is easy to get lost down the rabbit hole. The giggle AI search also does not help as it wants to keep you constantly engaged. On the other hand this is where AI actually seems useful.

I also have access to a CO2 laser which works great with acrylic. Which in a way could be ideal for the 1655 bezel, although it can be brittle. Was able to cut gears for a film slitting machine, and parts of a processing tank.

Vacuum forming is another option. This is were one makes a former, then the plastic (which can also be polycarbonate that does not laser well) is softened with heat and pulled down onto the mold.

Even today I modified some acrylic scraps for the coil winder. So I am thinking in the background how one could use this stuff for a bezel/crystal combo.