The cabinet was built of wood – essentially 1/8″ thin sheets of what we called Luan plywood on a frame of 1X3 pine – by the construction crew run by Bob Scaife at MGM. The wood was painted “as metal”, and given the hammertone finish in the final paint process. After the basic construction was done, but before final paint, my crew installed all the lights and circuitry to make the lights blink (a fellow named Mick Baron did that). I think you can detect the pattern of an early LED stereo equalizer display in there – built up from a piece of stereo hardware I picked up somewhere.
The flat panel display (the early flourescent type) that carried the countdown information was the only existing prototype of a display developed by a fellow I knew in Sunnyvale who I met through Paul Lovoi, then of InTA (International Technical Associates, formerly of ILC), who built the giant strobe system we used for the end
sequence. Paul was, and is, one of the most brilliant people I have ever met – he’s still in Sunnyvale and still inventing very cool stuff. I have drawn a blank on the display fellow’s name, but he was a well known inventor in Silicon Valley in the 80’s, and had quite a few patents to his name (Nolan…? Damn, why can’t I remember that? I may have to call Paul). Anyway, I hand carried the display on my lap from Sunnyvale to MGM, where I personally installed the display in the WOPR and then connected it to an Apple II with a prototype driver card for displaying characters on the screen.