Here is one more solution....many medical supply stores have a kind of hollow foam tubing in various diameters that slips over objects like pens, handles of eating utensils and even handlebars. They can make for a more comfortable grip for a sore hand. Many years ago I got an assortment of this tubing and it made my mom's life so much easier.

Thanks Karin!

As nice as these brushes turned out, they are hard and still hurt my hands by the end of the day. If I could find those tubes and fit them over the clay forms it might just do the complete trick.