In 1973 I was taking a FORTRAN programming class in high school. We would type our programs into a Teletype terminal and send them to a remote computer by putting a phone handset into an “acoustic coupler” on the side of the Teletype. When our programs were running correctly, we'd save them by punching a perforated paper tape, and we'd protect the tape by rolling it up and putting it into a film can. Those cans were metal - silver body and screw-on lid with a rubbery sealing ring on the inside lip. So, Kodak was still using metal cans as of 1973, I wish now I'd saved a few.