You would get at most one apparition's worth of goo from one apparition. The unique part Mathilde has is a constant, reliable supply that is unable to violently object, and it is only possible because of that specific apparition having a method of travelling between reality and the warp, and it was caught right in the middle of doing so in what is, to it, dozens of overlapping portals. That is what makes it able to regenerate but unable to escape. Trying to replicate that means playing silly buggers with extremely dangerous apparitions and portals to the Aethyr to try to replicate by sheer chance a vanishingly unlikely edge case, and can and should be considered impossible.