I'm not into alterations so I can't really help you there. Too bad there's only one shot of the dress. It looks like a variation of a Princess seamed dress, which actually is a more flattering style for most figures. Maybe using a Princess pattern and altering the front panel piece(s)would be easiest. Have plenty of extra fabric on hand or a practice fabric to start. Hopefully one of the more experienced seamstresses will post a better way. This looks fun and interesting...let us know how it turns out.

After posting I looked in eBay sewing patterns and found mostly fake costume patterns without the detail of the original, but then there was this...

Here is a link that might be useful: Star Trek pattern

The Fabric looks like a lycra dance fabric not really hard to work with as long as you use a needle for stretch knits or ballpoint needle. Test needle on faric to adjust the stitch length.
Suggest prewashing the fabric, pressing prior to cutting out pattern.
Your Pattern should be for a knit. Check Kwik Sew, they may have a top using 2 colors.
For every diagonal slash you must add a seam allowances.

Zipper: would use an invisiable type, stabilize the seams with the "seams great" (bias cut tricot) or something similar. Pre Shrink the zipper, soak in water let dry press.

Would probably use a double needle if hemming by machine, it would help the hem lay better also finishes the back of the raw edge, the one in the picture the hem is kind of sloppy, lot of puckering. Test the stitch on scrap.

Hope this helps..

I think this dress has a side seam. On the left the seam swirls down fro the bodice and on the right it looked like a seam on the hips and a free hanging overlap on the right. Note the hem on the right and you will see it's not joined.

There are star trek patterns, but I have not found them to correct to the orginal. It may have a side seam, I don't know, but what I noticed is the front seam. I took pattern drafting, and you can alter a pattern by slashing out or cutting out part in front, but it's not easy to do that. You must then ad seam allowance to the parts you have cut and then sew them together. I have the correct fabric a Lycra cotton blend, but I think the dress from 1968 would not be Lycra. I don't think Lycra was invented back then. I am going to make a some test prototypes before cutting the good fabric. Unfortunately, I took flat pattern drafting along time ago and I don't remember very much, but I have a dress form that I can try to do draping also and see what works. I know a plain test with a side seam will make any stomach expect for the most flat stick out. That's why the dress has the seams in front, which allow it to lie gracefully over the stomach instead of stretched tight.

Spandex/lycra was invented in 1959 and was being used from the 60s.

I was thinking I did not have any Lycra until the 80's, but that's good to know. I should go look at the dress, but they will not allow any photos of the dress, and it costs 25 dollars to see it. I think that is way over priced.

Found the site below, many pictures of the uniforms, if you click through some of the list on the left it will tell you that the orignal fabric was a velour did not wear well then went to diamond double knit, to whatever used today..
Lycra is another name for spandex.
At any rate the fabrics all had stretch and knits were used..

Here is a link that might be useful: Original Costumes

That's true, I don't think Lycra was sold in the 70's even, but maybe spandex for leotards. I really have to pay my $25 dollars to see what it's made of. Thank you for the great link. I like working with knits. People say they are harder then wovens, but they are more forgiving size wise.

This link says the original uniform was not spandex, but I understand the next generation uniforms were spandex. But, I am going to use Lycra anyway. If I don't it will will need zippers, and zippers are not my strong point. I just am interested in the different design.

Here is a link that might be useful: uniform wiki

FYI Lycra, Spandex and Elastane all the same... Honest

Know your using Lycra, no big deal unless your making it for a reproduction costume company for an exhibit.. IMHO I was just thinking if you made this and someone would compliment you and ask you if it was one of the three fabrics above you could say yes to any of the three different names.