(Yes, it’s stoff, not stuff–just playing with words on the silly page. “Stoff” is German for Fabric, and is found in the names of many elements as well.)
A Cornucopia of Chemical Crayons
QueInteresante on etsy sells these: a set of 96 stick on CLEAR labels with information about which chemical goes with which color and a chemistry lesson for the non-chemical person
Turns out the seller is a Spanish teacher in Fargo! See the web page here.