Creating an installer for OS X <= 10.13 under Mojave

[ProxiStyx]

Hello everyone,


I'd like to create a USB installer for Sierra or El Capitan. However, Mojave refuses to download the installer for older versions of OS X. Even if I download the installer from elsewhere and put the application in the Applications folder Mojave refuses to start the installation.

I'm not sure if it is due to this but in either way, I'm not able to create a bootable stick via Unibeast as there is either no installer or Unibeast recognizes the installer to be incomplete(?). Has somebody here already attempted this or is there maybe another workaround getting the installer?

Currently, my only option seems to be to reset my MacBook back to Sierra - if the offline recovery even allows it - and starting from there; but as you can imagine I'd like to keep this as a backup plan.

Any input is appreciated!

 

[Obvious Answer Man]

If you didn't save the installer you're out of luck.

Apple does still have El Capitan, Sierra and High Sierra in the MAS, but they are only available to download from systems running High Sierra or earlier.