I found this tutorial on a Russian website for making a perfectly round ball using LaDoll clay. The artist will use the balls for the joints in her BJD dolls, but I bet there's other uses for a perfectly round clay ball! This technique may also work for other brands of air-dry clay (such as Creative Paperclay). You'll have to experiment.
Google doesn't do a great job of translating Russian when it comes to crafting terminology, so I'll do my best to translate the important parts of the tutorial to English and then you can visit this site to see the original tutorial and all the step-by-step photos.
- For this tutorial you'll need a circle template made of plastic like the one shown above.
- With your LaDoll clay, form a rough ball of clay approximately the size needed for the joint...maybe a tiny bit larger. You can use foil or other armature inside the ball of clay. The ball doesn't have to be perfectly round at this stage.
- Let the clay dry and cure for 2-3 days.
- Dip a cured ball in water for about a minute so that top layer of clay is slightly softened, then put it in the circle cutout of the template that is the appropriate size for finished ball. With light pressure, start to scroll the ball around in the hole. The softened surface of the clay should sluff off to match the perfect roundness of the circle template (see photo).
- The ball will slip in your hand and be difficult to hold, so it's better to do the scrolling wearing cloth gloves.