Williams started using this door by 1972, and kept using it through 1985 for pinball.
Williams used their own coin door on Defender, but not many other videos, and on pinballs up until ’84, around Sorcerer.
Williams generally switched to Coinco doors after their door (starting around 1981 for video and 1985 for pinball) and then to Entropy doors (around 1988’s Taxi). They later dabbled in Coin Controls‘ DBV door as well.
For the “big shiny door”, coin inserts are available from many of the usual suspects including the Pinball Resource.