This is the same model of case used, and redressed, by the Prop Dept. to become a standard Starfleet-issue carry case. The found item used was actually an audio cassette carry case, called the "Dynasound Organizer Cassette Tote Case" (third pic was sourced online), and was widely available at the time the show was on the air. I plan on detailing it either to reflect the sickbay or engineering version (last two pics).
