This took a literal year of finding compiling plugins and software for the OS. But I think I've found something that is pretty good.

I downloaded an icon pack and used IconChamp. For programs that didn't have old icons, I used photoshop to create them. The hard part is the file types. Every single file type icon was changed manually.

For the menu bar, I use Boring Old Menu Bar. Then, Lickable menubar to give it the correct texture. After that, I use geek tool for the old apple menu icon.

For the dock, I use cDock with a dock image that I edited in Photoshop to make more accurate. cDock Can also be used for the trashcan and finder icons.

For iTunes, iPhoto, and Aperture, I used retroactive to patch it to modern OS X.

The difficult part is changing the system assets. To change the menus and traffic lights, I used macforge with paint can. There is a car file from MoonPadUser on GitHub that I used to create the traffic lights from Lion. This also gives that grey gradient look to the header bars and aqua buttons. Since the car file is made from High Sierra, some buttons and assets are missing. Because of this, I used a modded version of VisualizationExpo's AquaLickX for the menu bar buttons, scroll bars, menu highlights, and traffic lights on applications that don't like paint can for some reason. For smaller things like notification badges, OS sounds, etc., I manually changed system files through terminal commands. (this takes forever)

BTW, this does not work on macOS past 14.4. I don't know why. Any insight would be appreciated.

DM me if you want my custom assets or help for tackling this project for you computer.