For the armor in all honesty, the easiest would be to buy a fencing guard (women's obviously) then just adding subtracting as needed. I got mine that had the "2 boobs" configuration (for a lack of better term) but they sell the kind similar to Asuna in the "1 boob" configuration. For the detailing you can use acrylic trim to make it really pop. A knife and a heat gun will be all that you need.
Fencing guard undergoing modification
I've written several articles if you plan to fabricate the chest piece outright, it can be done, but it's just a lot of work (sanding, sanding and moar sanding really) http://junkerscosplay.blogspot.com/
You can see the acrylic trim on the bracer and upper arm armor.