Create macOS installers with Mac Deploy Stick (MDS)

Platforms
macOS
Products
MDSDisk Utility
Result
A bootable macOS installer on a disk image (.dmg) that you can use in a VM or for a clean macOS install

Overview

Create a bootable macOS installer on a disk image or USB drive with MDS (formerly Mac Deploy Stick), ready for a virtual machine or a clean install on a real Mac.

MDS (formerly Mac Deploy Stick) from Twocanoes Software is a tool for Mac admins that downloads specific macOS versions and creates bootable installers on a USB drive or on a mounted blank disk image (DMG). If you have worked with Windows Configuration Designer, the idea will feel familiar: both tools help you provision new devices.

MDS downloads macOS installers from several Apple software catalogues (Production, CustomerSeed, DeveloperSeed and PublicSeed), including beta versions. In 2021 that meant macOS 12 Monterey (beta), Big Sur 11, Catalina 10.15, Mojave 10.14, High Sierra 10.13 and earlier.

In this post I create a bootable macOS installer on a disk image. You can use it in a virtual machine, or create the same installer on a USB drive for a clean install on a real Mac.

Prerequisites

Before you start, check that you have the following.

What you need

checked 10/2026

Area What you need Docs
Licence An MDS licence from Twocanoes (from 600 USD per year for up to 200 Macs), or the trial MDS
Devices An Intel or Apple silicon Mac with macOS 15 or 26 to run MDS Requirements
A blank disk image of about 18 GB, or a USB drive of 32 GB that will be erased Apple
Apple The macOS installer you want, downloaded in MDS (Tools > Download macOS) or from Apple Apple

Configuration

First create an empty disk image as the target, then let MDS write the installer to it.

Create a blank disk image

In Disk Utility (or with hdiutil in Terminal), create a blank disk image (.dmg) to hold the installer. Select File > New Image > Blank Image:

Create macOS installers with Mac Deploy Stick (MDS) - screenshot 2

Choose these options for the new disk image:

  • Size: 18 GB (enough for the macOS installers in 2021; Apple now suggests 32 GB for a USB drive)
  • Format: Mac OS Extended (Journaled)
  • Encryption: none
  • Partition: Single partition – Apple Partition Map
  • Image Format: read/write disk image (so you can add files after it's created)
Create macOS installers with Mac Deploy Stick (MDS) - screenshot 3

Save the image and mount the new blank volume:

Create macOS installers with Mac Deploy Stick (MDS) - screenshot 4

Create the bootable installer with MDS

In MDS, download the macOS installer under Tools > Download macOS:

Create macOS installers with Mac Deploy Stick (MDS) - screenshot 1

Mount the downloaded installer (for example Install_macOS_12.0-21A5248p.dmg) so you can choose it in Select macOS installer. As the Target Volume I selected the blank disk image (macOS 12 Beta.dmg) from step 1:

Create macOS installers with Mac Deploy Stick (MDS) - screenshot 5

Select Create. The MDS admin helper creates the bootable volume with Apple's createinstallmedia command. You can also run the same command yourself in Terminal:

"/Volumes/Install_macOS_12.0-21A5248p/Applications/Install macOS 12 Beta.app/Contents/Resources/createinstallmedia" --volume "/Volumes/macOS 12 Beta" --nointeraction

Update (October 2026): Apple documents the createinstallmedia command for every macOS version in Create a bootable installer for macOS. For example, for macOS Tahoe and a USB drive named MyVolume:

sudo /Applications/Install\ macOS\ Tahoe.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

When prompted, select Erase and Create Bootable Volume:

Create macOS installers with Mac Deploy Stick (MDS) - screenshot 6

Result

After a few minutes the bootable macOS installer is ready on the target volume (.dmg). You can use the disk image for new macOS installations, or convert it to an ISO file if you need one.