Substance Designer can be set up to auto save every few minutes in case of a crash, which is something that happens a lot to me at least.
The problem is I couldn’t find the auto save files no matter how I tired they weren’t in any of the obvious folders, including the /tmp folder which would be logical.
So I did a little web search and found that the programmers in their infinite wisdom decided to put the back ups in a .folder called .autosave which seems logical enough. However on a Mac or Linux this is treated as a hidden system folder hidden by default from the user and Spotlight.
To make matters worse it creates a .autosave for every project and as you can imagine they can grow quickly. There are images in there as well so really quickly if you have a lot of referenced stuff.