This is "Scale Armor" kind of an apron that would protect the wearer's torso. It is completely made by hand. The metal plates are cut, the sharp edges grinded and three holes punched. They are hand sewn to heavy canvas in a woven pattern to inhibit sharp objects from penetrating. This is what it might have looked like: http://www.polandbymail.com/get_item_jk503_full-size-hussar-fish-scale-armor-helmet-with-stan.htm
I am amazed by his hand work, I showed him how to do a buttonhole stitch quite a long time ago and you can see he makes use of it here to finish the edges of the canvas. I guess sewing does run in the family!