I begin by marking where the seams will go on the plasticene with a Sharpie™ felt tip pen.
After sealing the clay with a coating of pink urethane resin, I cover it all with strips of masking tape. The resin is necessary as masking tape won't adhere to the clay.
Once I am satisfied with the pattern pieces I use an Xacto™ knife to cut off the individual masking tape patterns.
Now I test my pattern by cutting them in a thin cardboard, stapling and taping the different parts together. All looks fine, so I will proceed to the next step.