Originally Posted by
Sutekh
Pym's been size-changing for ages, and every time he shrinks to small enough to ride on an ant's back, 99.9% of his brain gets sent off to wherever all the extra meat goes (and the extra meat-mass comes from, when he grows to sixty feet tall). Not to 'do you guys just put quantum in front of everything' here, but there's pretty much got to be a quantum echo of his brain left over in whatever that place is, by now. His brain has been imprinted on that medium for years, off and on.
Tease those 'memories' or 'engrams' out of the surrounding stata, and it should be downloadable into a meat-body clone, either one grown in a lab the 'old-fashioned way' (like how Reed and Tony grew that clone of Thor...), or one made entirely from the 'meat-mass' of whatever place Pym gets his extra meat-mass from anyway (making it a one-stop solution, with body a new body *and* the 'residual quantum imprint' of his mind, coming from the same place, one, fittingly enough, entirely based on Pym-tech. and not anything to do with some other people's crazy comic-book pseudo-science).
Pretty much everything involved is in his wheelhouse already. He's been growing tons of his own extra mass for years. He's encoded memory engrams of himself and transferred them into Ultron. He's just got to be in a place, narratively, where all these ingredients can come together and make soup.
And, yanno, have writers / editorial who *want* him back...
That's the hard part.