All you need is an 8 GB (minimum) USB thumb drive, a USB, FireWire, or Thunderbolt drive or an SD-Card the OS X 10.11 El Capitan Installer from the App Store (once the download is complete the installer file will appear in the Applications folder - do not move it) and the DiskMaker X installer. Like the previous versions, DiskMaker X is free of charge (however, donations are accepted). Luckily, DiskMaker X helps fill the void by allowing you to make a bootable OS X 10.11 El Capitan USB install drive, making a task such as installing on several different machines easier. So if you previously relied on DVD installs, you won’t be able to do so with this version. And as with previous OS X versions dating back to OS X 10.7, El Capitan is only available for install via download from the App Store. With OS X El Capitan, Apple has built on many of the changes that were brought on by Yosemite. UPDATE 09/2016: Create a Bootable macOS Sierra Install Drive with DiskMaker X UPDATE 09/2017: Create a Bootable macOS High Sierra Install Drive with DiskMaker X 7
UPDATE 09/2018: Create a Bootable macOS Mojave Install Drive with DiskMaker X 8
