I just built one. Here is how…
First up, I purchased a mannequin off TradeMe - I think it cost about $40 but that was a year ago when I first decided to build this armour…
Then I chopped out a breastplate and backplate using a jigsaw. I used a heat gun to heat the plastic around the bottom edge so I could bend it out a bit and remove the serious builders crack between the buttocks
Then, because the mannequin was a little bit skinny around the waist, I added some extensions to the sides from 3mm leather…
Then I covered it in 2mm leather. It would have been easier with a lighter leather. I used ADOS F2 glue.
It fits reasonably well, but I may change the ties to buckles as they’re a little bit slow to do up and undo.