Cocos2d version 3 preview
Download: Cocos2d version 3 preview
Unzip to a folder of your voice. Open terminal and navigate to the folder where you unzipped. Type./install.sh. After this, you can delete the zip, and the unpacked folder.
In Xcode, you should now be able to create a new Cocos2d v3.x project.
Also, check the github page for more detailed instructions on how to download and install.
Note. Fat Chipmunk2D lib for OSX, is broken. Will be fixed asap.
SpriteBuilder can be found here, and the source code can be found here