Whether you are a Major contractor building a 10-story office building, or a small contractor painting a house, you should have a sign for the job site so that people know who's doing the quality work they are observing as they pass by. Job signs on corrugated plastic are perfect for the short-term job site. For a project that takes a while to complete, A temporary but sturdy job site sign is required. A large vinyl sign on MDO, exterior plywood, or aluminum is best.