You don't need to be artistic. You just have to be accurate at what you are drawing. My first day at dental morphology, we were told to draw the central incisor. So, the nicest looking drawing wasn't even a perfect one. (Didn't mimic exactly the contour). Don't panic, just make sure you pay attention to your details, and you'll get there. Your ability to draw doesn't relate whether you are a good dentist or not. You will take longer time to master your carving, and eventually will get it. (Hope not having to repeat the prostho class). Just remember that once you are a dentist, you can send all your lab work out.