To add a liner to the base or top of your polymer clay box to help the sections fit together, first gently remove the two halves of the box from the former. Cut through your dividing line again if necessary and use the side of your blade to gently shift the top and bottom of the box off the former.
With the two box sections separated, roll out a thin strip of polymer clay, wider than the side of the section you intend to line (by 1/16 to 1/8 inch). Carefully insert the liner inside the top or base of the box so that it sticks up above the side of the box on the inside edge. (see photo). Gently press the lining strip in place all around the inside edge of one side of the box (top or bottom, your choice). Set this box section aside to be baked when the top is decorated.
