Created this for use with cosplays of the recent cinematic version of Thor.
This specific circle corresponds to the bottom set closest to the waist. The other sets of circles can be created by scaling this circle up.
The base armor circle measures approximately 2.5 inches by 2.5 inches by .25 inches.
Finish it with a sealant and a nice coat of chrome spray paint to complete the look.
These armor elements shouldn't require supports to print.