Angela - the secret to all of these "curved" lines is to recognize that NONE of them are curves. They are all straight lines that curve due to one of two causes: either the barrel is turned or the blank is angle cut. To reverse engineer any of the glue ups you see, simply create a two dimension view of the object with straight lines, for example, a pin wheel. Wrap it around a pencil and you'll see what happens. Take at look at Russ Fairfield's site and you will see many of the same figures in bowl form.