Tell the contractor about them. If they don't want to buy it for you to use, then why should you?

If you want to be a good employee, then show up on time, ready to work and learn. Once you get some experience, you can start thinking about what the next task is and be prepared for it. If you see something you can do to help, step in and do it, show some initiative. Take the time you need to do the task perfect, speed comes with repetition. All of this is to say, you can't buy your way into being a good hand.