So today's Hobby is Dust allies' armor. It will only be showing the chest armor today. So I can't really give you a template to use because it would be different for each person. I used foam core to made the armor. The best way to get measurements is to lay on the foam ore and get you shoulder to arm pits marked, your waste marked, and your neck then connect the dots with curves.
I can give you what I made for the front. I put extra to the end to trim when I fit it.