Portal 2 owners can finally try their hands on the easy-to-use level editor, as the Perpetual Testing Initiative DLC has arrived today for the PC and Mac. Steam should already have started the download for the DLC, but if not then just reload the client. Once PTI is downloaded, you can try your hand at making any number of puzzles that you can dream up. You can then put your puzzle on the Steam Workshop so other Portal 2 owners can give it a try and leave you any feedback. Any puzzles you select will be automatically downloaded, so you will not have to worry about any kind of an installation process to jump through. Just fire up Portal 2, launch the user content section, and start playing to see if any other gamers are as diabolical as GLaDOS. Remember, testing is a necessary part of Aperture Science, so do your part or Cave Johnson will fire you!