How the hell do you get negative matter?

[deathrobotpunch]

So recently someone put me in a negative matter locker, I found that it’s dimensional storage properties would be very useful to use. So I look on the wiki, forum and online and there is no information whatsoever and the most information I have found was little code snippets but nothing on how to get it.

Unless it’s an admin only metal please tell me how to get it!