Valve has made the beta Portal 2 Authoring Tools available for free for owners of the PC version of the game.
Downloadable through the Tools section of Steam, Valve has said that the kit will include a version of the tools used by the studio during development.
These tools allow for the creation of co-op and singleplayer maps, character skins, 3D models, sound effects and music.
The full kit will include an updated version of the Hammer Source level editor, an updated Faceposer, example maps and an updated suit of common-line compiling utilities.