In "Mirror, Mirror" from Star Trek: The Original Series, original-series art director Walter M. Jefferies needed to show that the Enterprise from the evil Mirror Universe was different from the starship from our reality. One of the ways he did this was to stencil a distinctive planet-and-sword emblem onto the doors in the Enterprise corridor. Nearly four decades later, Star Trek: Enerprise production designer Herman Zimmerman wanted to do the same thing in the corridors of the Enterprise NX-01 for "In A Mirror, Darkly" from Star Trek: Enterprise. The problem was that the shooting schedule required some of the doors to be converted back and forth between their "normal" condition and their "Mirror Universe" selves. Also, Zimmerman's plated design for the NX-01 doors made it difficult to apply graphics using stencils. The solution was to apply the planet-and-daggar symbol to thin sheets of rigid plastic that could be placed on the doors, yet easily removed when necessary. As a result, this artifact from the Mirror Universe could be applied to nearly any door, but it is also suitable for shadowboxed display.