This is a craft designed for masses of elementary school students to do with relatively little adult help. It was directly inspired by Kiteman's Climbing Gorilla; think of this as the fast, cheap and almost out of control version (250+ made in 3 hours by young people ages 4 to 12). It was easy to set up and get supplies for, which were about $60 ($20 of which were markers).
Step 1: Assemble materials and tools.
Scissors to cut straws and string
Computer to print out original butterfly sheet
Copier or copy store to make multiples of sheet.
(Only for at-home version: glue gun)
Transparent tape (not required for at-home glue-gun version)
String (White cotton household string is what I used; kitchen twine is fine; whatever the drugstore down the street from the event has in stock mid-event also turned out to be fine.)