This is my version of the Captain America Shield. I've modeled both the front and back along with the connectors and buckles needed to wear this. You need to bend a 1/8" wire in this sort of "U" shape- |___|- For the far edges of the shield. My thinking is you'd route out a trough for the ends of the wire into the main shield then glue the "Strap_Base" over it to hold the ends in place and allow it to pivot some. If you print the "1 section" file 5 times and glue it together you'll get one complete Main shield that you can then add the other parts to if you'd like to wear it.
The exact dimensions of the shield vary some from prop to prop/movie to movie. I made this one 26" in diameter by 3.5" in depth. My thinking is that would be a good wearable size that I could print on my CR-10 S4 without too much difficulty.
I'm test printing this now and will post an update if I run into any problem. Enjoy!