How to create a bootable installer for macOS

There is a new version of macOS out (at the time of writing 10.14 Mojave) and you want to upgrade. For the past few upgrades and this one Apple provided the update via the App store. This is all fine and well if you have a good unmetered(uncapped) internet connection to download the +- 5Gbyte installer. The big catch with the installer is if you follow the default install procedure the installer deletes itself after the install. This if of course a real problem if you want to update more than one Mac, especially if you pay per byte for your internet connection or if it is really slow. Read more