Each script requires a certain number of items in order to create the world they're living in, so, there needs to be someone who isn't designing the sets or running around putting costumes together to simply focus on the gathering of those items.
This is where your prop wrangler comes in. Need a hacked off arm? How about a vintage Esquire magazine? No? Oh, you need a blackboard welcoming back the class of '88 on one side, and a large penis drawn on the other side.
Well, talk to Brian Stricklan, he may have answers for you: