So far I was thinking it could be air fill in, for the clothes material itself, I haven't thought through yet. Those are really great inspirations! Thanks Kate!

Yes, it's a very great example. I kind of want to hide it inside the clothes, just in case some elders might not want to be covered like the one for the helmet. But we definitely can explore more on that. Thanks Harrison!

About how to deflate, I think a certain kind of clothes material might be able to help, by releasing the air slowly in a way, as a buffer, or could be like what Avery mentions, which is a good point as well.