That is a beautiful idea, lol. Just a bit worried about making sure the edges fit flat against the sintra so there aren't bumps. Definitely something I can experiment on
Actually, no, don't do that. Like, ever. That's a horrible idea, and I'm pretty sure he was joking.
Do either-or. If you can swing real metal armor, do it. If you can swing sintra, do it. Do
not attempt to overlay the plates like that, mainly because it's kinda completely pointless, and I have serious doubts that it'll work without causing damage to the Sintra plates (in order to curl those steel plates in, you're gonna need to give it a few solid
thwacks with a hammer, and sintra wasn't made for that kind of abuse).
If you want metal plates (I always advocate steel plates over sintra, for a variety of reasons), pick up a used car hood from a collision shop and cut them out. If you can cut your plates out of the sheet metal you're using with a pair of tin snips (it looks like you did, here), it's not gonna be thick enough to be usable.
How thick is that, anyway? At a glance, based on the cut marks along the edges, it looks around 26 gauge. How easily can you bend it with your hands?