There's a different resource management system in place for Dead Space 3 that goes toward building your own weapons from the ground up. You can find items throughout your adventure, or you can just be lazy and buy items through the microtransaction option that comes up every time you want to build something.
Or in the case of this little glitch that Game Front discovered, you can exploit a specific room in chapter 8 of the game so you can infinitely get items over and over again. Nice.
Dead Space 3: Infinite Item Spawning Location [Game Front]
via destructoid http://www.destructoid.com/dead-space-3-exploit-already-found-for-infinite-items-244024.phtml