AliExpress seller “Gamers Zone Store” has Joy-Con shells that seem to be coming off the same line as the real ones — same finish, same regulatory markings, same casting marks — and they just got right-green. So I just got right-green. Now it is always green.
Not too bad of a job — maybe 50 minutes for both, with a few fiddly ribbon cables, so it’s definitely a tweezers job — and then you pair them to your computer and use Joy-Con Toolkit to change their color in software so that they show up green on the Switch.
