[6] Besides creating interiors and exterior of the Enterprise, Jefferies was responsible for designing props (including phasers), sets, the Klingon logo and D-7 battlecruiser.

Years later, his concept sketches were revisited and used to design the Starship Enterprise, the Olympic class USS Pasteur, the Daedalus-class and pre-Federation Vulcan ships.

Figuring that whatever could go wrong would, he put all of the ship's workings on the interior for easy access, eliminating the need for spacewalking in case of exterior repairs.

[citation needed] Moreover, he disliked the idea of a large engine room because by his reckoning the entire ship could be run by a single panel on the bridge.

[citation needed] Later, Jefferies' work on the bridge of the Enterprise influenced the design of the U.S. Navy master communications center at Naval Base San Diego.

[11] In June 2003, Jefferies was the guest of honor at the presentation of a documentary about him prepared for the special edition of the Star Trek Generations DVD.