User blog comment:B214/Question and Answers 3/@comment-114.4.21.209-20140828035639/@comment-1359322-20140901023125

Well it's a matter of the medium of materialization too. The body needs to act as a medium for the activation of SG, so it can in fact be taken from the body even if it doesn't have a form. But do know this, we still haven't know whether or not Dimension Lost and Annihilation Maker are formless, it might have one but the LN didn't mention it.