i recon you should have methane, which only burns when touching oxygen. it would be called MTHN.
also a pressure equaliser, which wuold be a tool to equalise pressure, and it could also be an element.
also an unbreakable goo, which deforms, but dosen't dissapear.
oh, ok. just saying that would dissapear in 99999999 frames, and some people don't know how to use the console.
!set life goo -1 would mean it never gains life, so it can never lose life and therefore cannot dissapear.
still, if you can make it with the console, then it shoudn't be too hard to put in a mod.