My calla lily candle holders are one of my most consisent sellers of my more art type pieces. I intentionally make them all slightly different. My goal isn't consistentcy, it's that each set is unique.

The first one I make always starts off rather rough. I have to remember how to roll them. By the time I've done the 3rd or 4th I have it down. The biggest key to these is to not try to do it when the clay is too wet or they will not stand. This is true of anything that's taller than about 3-4 inches. You want the clay to still be moldable, but have stiffened up enough to hold the weight.