Thinking about buying a second grey set and modding them into either the atomic purple or the smoke translucent (if I can find those) that someone posted before. But I don't know how to choose from the myriad of sellers on ebay. I imagine quality can vary and it's kind of a lottery with these sellers...
App called Joy-Con Toolkit. Very easy to use and does it via bluetooth. Mine were grey.
Everyone using the rainbow buttons from the custom kits, those letters are just painted on and will rub off. I kept the original black because they're double injected plastic. Also sexier.
I've got the red from the Mario bundle. I'd like to get some black ones for whenever I take the Switch out. And I also want a pair of neon blue and red. I have a blue Xbox controller and a red DS4, so those joycons would look perfect on my desk.