There are a wide variety of costumes to choose from, but both organizations require that a costume pass an approval process before you're allowed to "troop" in the costume in events as part of the organization. While the specifications for a given costume can be demanding, the panelists all stressed that there is a great support community in the organizations and that things are much easier if you ask other members for advice and consult the many tutorials on how to create your own Star Wars costume.
"Princess Sandy" was present as Princess Leia, in the white dress from the original Star Wars movie (A New Hope) and she showed some of the minute details that must be authentically replicated for the costume to pass the inspection process. For one thing, the hood on the back isn't a full hood, but a half-hood, such that when pulled up over the head, the back of the head remains exposed. If you try to get approval with a full hood, you won't get it. Also, the belt for this costume features several metal plates of a certain shape. In order to be accepted, this belt must have these plates and the plates must be made of metal. There must be at least seven of these plates, but the eighth plate, located at the rear, is optional, since in some shots in the original movie, Princess Leia has a plate there and, in other shots, she doesn't. Other items that were mentioned as having specific requirements were the boots and the slits on either side of the dress. Then, of course, the hair has to be right.
The two men present on the panel both wore Storm Trooper costumes, which require a great deal of "hard" pieces, as they refer to them - pieces made of fiberglass or ABS plastic. Additionally, they too have certain boots that are required and the hard parts need maintenance from time to time. One thing that both stressed was not to purchase a costume from a company or, worse yet, on Ebay and expect that costume to be approved.
