Decided I wanted to print myself a set of Miles Vorkosigan's ImpSec silver eyes. There are pins of them available online, but they're just not quite how I envisioned them; these are a lot more like what I saw in my head.
Make sure you've scaled them the way you want them before you print—these are a little big for most anyone's collar in real life, although they're maybe about right for a cosplay prop meant to really stand out.
This is remixed from a very nice Eye-of-Horus keychain by Thingiverse user 2c2know. Thanks to them for a great base to warp and tweak!