UniBeast is a popular tool developed by that simplifies the process of creating a bootable USB drive from a Mac App Store version of macOS. It is a cornerstone of the "Hackintosh" community.
The most reliable source for legacy software is the or Internet Archive . Search for UniBeast 10.3.0 archive.org . You are looking for a .dmg or .zip file with a file size of roughly 5-6 MB (the tool is small; it’s the macOS installer that is large). unibeast 1030 download top