If you wanted to measure your body composition and only had a scale and measuring tape, what types of methods could you use?

Body composition, or the percentage of fat in comparison to the percentage of muscle, bone and water in your body, is hard to measure with a scale and measuring tape. Using existing measurements about bone weight based on size that you could find through research, if you measured the length of your arms or legs or your chest size, that could potentially tell you the size of your tibia, fibula, humurus, radius and so on. The scale would be able to tell you how much you weigh overall.