Not to discourage you but peps are sometimes really complex and even with a simple one cutting out all those pieces of sheet metal to fit the inside would be close to impossible. For a full suit you would be looking at cutting anywhere from 1000 to 5000 small pieces of sheet metal, and then soldering all of them together. This would take an extreme level of craftsmanship and wouldn't look very well and if you did make it look good with resin and bondo then that would probably crack when hit by a shot. Also I am unsure if the metal would even hold, you would surely get some major dents in your armor or have peices be falling out unless you put like 100 pounds of solder in it, which brings me to my next point, the suit would be extremely heavy. This would make you play badly, Most suits on here are fairly heavy and running around in one for a while is tough, add metal too it and you are going to find it hard to walk after 10 minutes of running. I hope that doesn't sound mean I am just trying to say that these suits are costumes and aren't meant for paintball and airsoft, if you were going to make one though I'd have to say make it out of thick EVA foam and I wouldn't spend too much time on it if you will be playing in it, last thing you want is your prized suit getting destroyed in a few matches.
Again sorry if that sounds mean I just don't want to see someone make an awesome suit and not be able to use it or have it be broken. However you tackle this though, I wish you the best of luck.