As he began to think more about how the shuttle needed to dock with the Enterprise, Probert started to move the nacelles forward to get them out of the way.
He really hit gold when he decided on the "Personnel Pod" that would separate from the drive or engine unit.
Probert was influenced by the Vulcan designs in "Amok Time." If you look at the back of the nacelles you'll see the shape is the same as the chimes and gongs from Spock's koon-ut-kal-if-fee.
Roddenberry approved of this final sketch and the designs went off to the Robert Abel model builders.
The finished model was so popular that AMT/ERTL created a model kit of it in 1979. It has remained in production since then. In fact, the kit was recently re-vamped with new box art by Andrew Probert. The original model was so popular that it was sometimes loaned out for displays at Star Trek conventions. Unfortunately, it was stolen from one such event and has been lost. At least collectors have the very accurate model kit.
In 1979 fans were delighted to get their first glimpse of a Vulcan spacecraft and, numerous toys and models later, the design remains popular. It is distinctive in both form and colour and it would influence the design work of later artists working on Vulcan spacecraft.
I'd like to thank Andrew Probert for agreeing to allow me to post his artwork here. To see more of his impressive work, please check out his website: Probert Designs