Select Okay and then, to confirm that you’re aware the volume will be erased, click the Erase then create the disk button. If you’re using a thumb drive that has only 4GB of free space, Lion DiscMaker will remind you that you won’t get a complete of OS X Lion package because there won’t be room for the “additional speech voices” package. Select your flash drive and you should be ready to rock. Select the USB thumb drive option again and when prompted, choose the disk that you’d like to install Lion to. Once you’ve indicated that you want use a bootable drive, the app will ask whether you’d like to use a USB thumb drive or some other kind of disk. Image via Step 4: Drag your USB (or a Dual-Layer DVD) drive from the list on the left into the 'Destination' box and click 'Restore' (or just click the 'Burn' button in the upper left if youre using a Dual-Layer DVD) and in 10-30 minutes (depending on whether youre using USB 2.0 or 3.0) youll have your backup disk ready to instal on as many Macs as you like. Lion DiscMaker makes it easy to create a bootable thumb drive. I prefer keeping Lion on a USB keychain so that I can add files to the USB drive to customize the installation but if you’re just looking for a bootable copy to troubleshoot your hardware, feel free to go with the DVD option and save yourself a little cash.) (If you happen to own a Mac with a disc drive, consider creating a DVD backup of Lion. The app will give you the option of creating a bootable drive out of either a DVD or a USB keychain. Start the Lion DiscMaker app with your USB flash drive plugged in and with the Lion install file sitting inside your application folder. Lion DiscMaker makes this part of the process a snap.

You have been warned! Creating Your Bootable Drive Now, before you start formatting your drive, back up anything currently on your flash drive that you’d like to keep–because this process will completely erase the contents of the USB drive and rewrite it with a copy of Lion.

How to make a bootable usb mac lion