Appearance Maker
Create custom appearances to customize your app's look with NSAppearance
OS X El Capitan
The current version only works on OS X El Capitan, Yosemite changed APIs and completely broke Appearance Maker, with El Capitan this project is usefull again.
This is a complete rewrite, there's a lot missing. I'll be pushing new stuff frequently.
What's NSAppearance?
Check the docs. Even though Apple states you can create a custom appearance using Xcode, this is not currently available, so I've created this app that lets you make custom appearances.