it is sintra like material different brand. I made the dents by boiling water in a big pot, laying the armor in water for a few seconds, then while wearing gloves I took a big Marble, and a CO2 cart. and pressed into the armor with all my might. then I reheated it a little and smoothed out rough spots with my fingers, While wearing gloves I used leather gloves. and then quickly put it into cold water. Worked slick.
I have not gotten to making my back armor yet though because I need an extra set of hands.