Lots of incorrect information in this discussion. The Disney Stormtrooper armour is made by Costume Armour in Cornwall, NY. The owner of Hangar 11 worked for us at the time and is responsible for many of the molds and suits created for Disney but his company does not make the armour.
Here is a link to some of the items we have made:
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The original set of 20 Stormtroopers was made at a very low cost to get our foot in the door. Since then we have made armour for Clonetroopers, Darth Vader, Zam Wessel, Darth Goofy, Stormtrooper Donald and Captain Rex and Rex's blaster. We also made the headdress for Queen Amidala.
The Rex armour was just a Clonetrooper with a few adjustments and additions. Disney was not willing to pay for a completely accurate version. We always want to go for the most accurate version but Disney often is not willing to pay for the new molds. They also make demands that we mix styles between the episodes. On top of that there are stringent requirements for durability and comfort for the performers which sometimes compromises design.
We do all the sculpture, mold making, vacuum forming, assembly and painting here at our shop. We are not allowed to sell the armour directly due to the involvement of Lucas Licensing. The suits are formed in Kydex T, which is a PVC/acrylic blend. It is similar to ABS but stronger and fire retardant.
I do have photos of the assembly of the parts that I would be willing to share. Just let me know what parts you are interested in and I will post them.