One of the jobs I do after a new Mac OS X release is to create a bootable install disk. Generally this takes a little effort with some messing about in the terminal and with disk utility but it seems Apple have created a little utility to do the job for you.
Basically fire up the command line, switch to an admin level use then just type the following: (assuming your blank media is called Untitled)
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction
That is all you need to do.
If you want more information check out Apple’s support site.
