While the game might be over two years old, id Software isn't done with RAGE just yet. After releasing The Scorchers DLC at the tail end of 2012, the studio has announced that they will be releasing a full suite of mod tools for the game later today.
The RAGE Tool Kit will include the very same world building tool that id Software used, called idStudio as well as game maps and assets to help you on your way. RAGE was the first idTech 5 game so this is the first change that the modding community has had to really get under the hood and see what the software is capable of from a modding perspective. The download is pretty decent at 35+GB so make sure you set aside a nice chunk of time to get the Tool Kit on your computer.
idStudio 5 sounds nothing short of amazing if the official description is anything to go off of:
idStudio is your main world building tool -- it includes a multitude of components to get your new RAGE mod up and running. Use it to get an overview of the editing environment, or to learn about the various browsers and windows you will use while creating your masterpiece. You can also check out some of the toolbars you will encounter, or view the master list of key commands.
Once you are familiar with idStudio and its features, take a look at the tutorials for a few step-by-step lessons on building environments.
Check out RAGE on Steam at http://store.steampowered.com/ and make sure you stay tuned later today when the RAGE Tool Kit becomes available!
Source: Bethesda Blog