They were originally made by ITT/Schadow, which was then bought by C&K.
Still available, you basically put your own kit together (LEGO-style): switches, buttons, U-profile for mounting, release springs etc.
Product name is C&K F-Series pushbutton switches. I attach a data sheet:
https://www.ckswitches.com/media/1402/fpush.pdfCheers.