The crafting system is simple enough, you must have a blueprint, the weapon or group of weapons the blueprint calls for, and the items that are used for the modification. (relevant-gaming.com)
New weapon blueprints are waiting for you to build the newest innovation in Necromorph obliteration. (thatvideogameblog.com)
GameStop: «Guerilla Care Package: Five Resistance Crates full of random weapon blueprints, attachments, equipment, and more.» (gamerassaultweekly.com)