Original Series Personal Transporter Development 

Cool! I believe that pattern was also used in the hallways on the Enterprise, too. Along the ceiling as dividers or something. Most likely designed to help hide that the ceiling was open, as well as hiding the set lighting.

Mike and Denise, maybe you learned your lesson today. Don't mess with Joseph.

Hey man, where you get that fabric? Harry Mudd's Girls...Even Mr. Sulu would take notice...