In this post I will be showing you how to partition your USB stick and make it bootable with 9 versions of macOS. Starting from Snow Leopard all the way to the newly released macOS 10.15 Catalina.

Why do we need that I don’t hear ya asking ? Well it’s for all you techies out there, that deal with various people, helping them restore their Macs, both new and old to factory. Once done this USB thumb drive will prove invaluable to you.

Now on to the tools you will need to do this. Mind you, this will take a while, so grab some coffee, put on some of your favorite music tracks, put on some headphones, sit back and relax while doing this.

Apple computer with OS X 10.9+
64GB or greater USB Thumb Drive. (USB3 is best)
All versions of macOS.
A lot of patience 😉

When considering the requirements, particularly the flash drive size and speed, I recommend accommodating a minimum of 9 or even 10 GB per OS X installer and preferably supporting USB 3.0 specification for faster file transfers as opposed to USB 2.0, which will work admirably, but slower. Also, since many Macs include SD card readers, a large capacity SD card could be used instead of a USB drive as well.

I. Partitioning the drive

For the purposes of this article, I’ll be creating three installers of OS X: 10.8, 10.9, and 10.10. However, the limit is really based on the total capacity of the drive to be used.

Launch Disk Utility.app and partition the external drive as three separate partitions of 8 GB each. I suggest naming each partition with the OS X version that will occupy the space to make it easier to identify later.
Click the Options button, select the GUID Partition Table, and then click OK and Apply to commit the changes.

With the drive now partitioned properly, see the sections below to go about copying the media/installer contents to the drive. Certain versions of OS X will require a different procedure to complete.

Lion

II. Apple OS X 10.7 (Lion), 10.8 (Mountain Lion)

Right-click the installer and select Show Package Contents from the context menu (Figure C). This reveals the contents of the installer itself and makes navigating the structure possible.
Drill-down through the Contents | Shared Support directories and drag-drop the InstallESD.dmg to the desktop.
Launch Disk Utility and click on the partition to copy the install files to, then click the Restore tab. Next, click the Image button next to Source and point to the InstallESD.dmg file recently copied to the desktop. Next, drag-and-drop the partition created on the USB to the text box next to Destination.
Once the source and destination fields are selected, click the Restore button. You’ll be prompted to confirm that the process will erase the contents of the partition by clicking Erase.
The process takes about 30 minutes, depending on the speed of the computer. However, once it’s completed, the partition will be ready to be used to install OS X. Simply repeat the steps in this section to create an installer for 10.7 and 10.8.

Snow Leopard

III. Apple OS X 10.6 (Snow Leopard)

Since OS X (10.4, 10.5 and 10.6) were released as bootable DVDs, the process for these is slightly different and significantly slower, because the optical drives read data at a far slower rate than mechanical hard drives and solid-state drives. For this process, either the original DVD media or ISO/DMG images of the DVD are required.

Launch Disk Utility and click on the partition to copy the install files to, then click the Restore tab. Next, click the Image button next to Source and point to the DVD drive or ISO/DMG. Drag-drop the partition created on the USB to the text box next to Destination
Once the source and destination fields are selected, click the Restore button. You’ll be prompted to confirm that the process will erase the contents of the partition by clicking Erase.
The process takes about 30 minutes, depending on the speed of the computer. However once it’s completed, the partition will be ready to be used to install OS X. Simply repeat the steps in this section to create an installer for 10.4, 10.5, and 10.6, as needed.

Newer

IV. Apple OS X 10.9 (Mavericks) and 10.16/11.x

By default, OS X stores the installers downloaded from the Mac App Store in the Applications directory. If your installers are stored elsewhere, modify the path accordingly. Also, “Untitled#” should be changed to reflect the name of the USB partition that you’ll be copying the installer files to. If you named it by the version number (10.x) as recommended above, you’ll use that for the volume name.

Depending on the computer’s specifications, the process takes approximately 20 minutes/OS to complete. However, once it’s done, the partition will be ready to install OS X.

Launch Terminal.app and enter the following commands :

- Mavericks 10.9.x :
sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled3 --applicationpath /Applications/Install\ OS\ X\ Mavericks.app --nointeraction &&say Done

- Yosemite 10.10.x :
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled4 --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction &&say Done

- El Capitan 10.11.x :
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled5 --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app --nointeraction &&say Done

- Sierra 10.12.x :
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled6 --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction &&say Done

- High Sierra 10.13.x :
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ High\ Sierra.app &&say Done

- Mojave 10.14.x :
sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled &&say Yippee

- Catalina 10.15.x :
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled &&say Yippee

- MacOS Big Sur 11.6 :
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume &&say Done

- MacOS Monterey 12 :
Coming soon...