I just finished a costume of Captain America for a someone going to Animaizement in Raleigh, Memorial Day weekend 2015 (she's the one on the left in the blond wig.)
In December 2014, this artistic student came into my sewing room with a printout of the Captain America she was hoping to go as. The picture was all I needed to get on her page. We talked fabrics, color, and design -- specifically how to get the jacket on and off.

Choosing garbadine for fabric because of the natural stretch which makes for a very comfortable wearing pant. I sewed zippered "pockets" to the front to match the original costume. These do not open to real pockets like I'm certain Captain America's do.
Next was the jacket. Two things things needed to happen -- it needed to open without having an exposed zipper and it needed to have stripes attached to the lower half. Using a pattern for a fleece jacket with a zippered upper half was perfect. I used the upper half for the blue part of the jacket and lower half of the pattern for the red and white stripes.
Having no luck finding red and white striped knit in the width I needed, I decided to sew strips together.

I added detail to the sleeves - strips to the upper arm and shield like shapes to the inside of the lower arms.

There are three main components to the utility accessory - the belt, two wide pieces that slide over the belt and the six pouches that attach to this wide pieces (three on each side.) The belt is attached with a metal quick release buckle.
The pouches are made much like an exposed pocket on cargo shorts with stiff interfacing so everything held its shape. Attaching a few more pieces of metallic fabric to the front flap of each pouch and a piece of velcro to keep them closed, the costume was complete.
Thank you, Amanda, for asking me to help you transform into your version of Captain America for a weekend.