"This one looks dead easy to make and large enough for some payload (with a second motor):
https://www.youtube.com/watch?v=SdjJWZSJzhw
I think collisions can be easily avoided by launching the individual aircrafts with, say, a minute delay, one after…"

"Puffed rice might be a good material! ;) Thumbs up, great project! I would be happy to donate a few bucks, if that helps."