I use Illustrator to do my designs then print them out, laminate them in clear packing tape strips, then cut them with an x-acto knife or scissors. The patterns stick just enough to the clay and are flexible but do not get wet. If I need to replace, I just print another out. Drawing in Illustrator allows me to to scale, match pieces of slab to each other, take measurements while throwing, compensate for shrinkage etc. I highly recommend for some applications.