The body armor I am making is based on this Italian example in the Metropolitan Museum. It is a kind of brigandine which features a split version of a style of breastplate, called a goblose breastplate, which featured prominently from the late 14th into the 15th centuries. Also called a corazzinas (though I can find no historical source for this name), it is one of two complete brigandines found in the so called "Chalkis Hoard," named for the castle on the Greek Island of Euboea, a powerful Venetian outpost in the late middle ages. Of course, I will be taking some creative liberties and making what I feel to be improvements on the design, particularly in the skirt, which underwent some "reworking" in the 1920's.

I started with a very large sheet of 14 gauge mild steel. Before I even cut the metal, I made the entire suit out of cardboard and sized it that way.
The first piece I made was the split globose breastplate; these were by far the two largest pieces of the armor and took quite a bit of pounding to dish to shape. I was constantly sizing and checking. There is about a two centimeter overlap on the plates, and both were flared out slightly at the bottom. the backplate goes down to just below my shoulder blades and will have nine more plates that will move the same way as my back.
Unlike the example above, I chose to make the skirt out of horizontal lames. I made this out of cardboard before cutting it out of metal as well. The lames have about a centimeter and a half of overlap, and I test fitted them by holding them together with duct tape.
This was the test fit of the front two sections. The breastplate goes just below my ribs so that I can bend and flex, and I will continue to add lames to go just blow my hips.
Though I found no historical examples of the two plates just under the arms, I found several examples of the backplates with the curved shapes cut out near the armpits, and the three plates at the waist are flared on both sides.
Once I completed shaping the plates, I drilled holes for the rivets, a centimeter away from the edge, in all the places where the plates will be riveted to the covering. I did not drill the holes for the straps yet, since they need to be sized precisely and will be marked after the three sections are complete. Before I covered the plates, I sprayed them with a protective paint to prevent rust from forming.
For the covering, I looked at several examples, both historical and reproductions. While many I see have covering such as linen, wool, and reinforced velvet, the one that attracted my eye was a beautiful reproduction of a Munich style Brigandine which was covered in black suede. For rivets I used galvanized roofing nails and small washers on the back.
For straps I could have used veg-tan leather, but instead I chose a more durable leather called latigo. Latigo comes from the Spanish word for whip, and it's durable yet supple qualities make it the perfect tan to use for straps.
For the front and side straps, I cut the straps to three-quarter inches wide, but for the shoulders I made the straps a half inch wider to both support the weight and distribute the weight over a larger area on the shoulders.
Like the suede, the straps are connected by roofing nails which act as rivets.
In addition to the brigandine, I also made a set of voiders and skirt which act as supplementary armor both to fill in the gaps plate can't cover and protect the straps and lacing for plate arms and legs.
Assembled
Back and side view.