Hi John!
I bought a couple of packages of 12"x12" mirror tiles and I was using those but it makes it hard to get a good picture from my camera with all the reflections. I sandblasted one of them a long time ago and I tried it but I don't remember what I didn't like about it. Ultimately I opted for a sheet of regular glass and cut it to the size I need, but I still have that sandblasted mirror tile so I'll give it another go.
I was also going to suggest PETG for gears. Most of my filament is PETG. It's easy to use but it tends to be stringy and that's one of the reasons why I put a camera on the x-axis carriage a few months back. I've seen the filament bubbling at the tip of the nozzle with PETG before but didn't connect the dots as it being wet, and it still prints beautifully, so I would say that PETG doesn't absolutely need to be dried unless you are after maximum performance. But the Alloy 910...the first thing I noticed is that right after I changed filament, I extruded 150mm to flush out the hotend, but then it just kept extruding/oozing out of the nozzle. As I'm watching it, it looked like there were lumps in it. I always watch the first layer, all the way through...if I don't have an absolutely perfect first layer, I cancel the print and start over. The first layer looked lumpy, like the material hadn't melted completely. I dried it in the food dehydrator/filament dryer at max (150-160F) until the next day (about 18 hrs) and then fed it out of the dryer into the printer. I printed it while the dryer was running. I don't like to run the dryer in the room because it gets too hot in there after awhile so usually I put the dryer outside while drying, but I put up with it in this case. When it's dry it comes out of the nozzle just like creamy toothpaste. I didn't think I would like printing it with a raft, but the raft prints like a plush down comforter and peels away easily, leaving a nice surface finish.
Speaking about surface finishes...I printed the CR-10s camera mount with support and it produces a woven kind of finish, not entirely unattractive...
Here's the other side (Hatchbox Black PETG):
#3D
