MARTI MICHELL: One-derful One-Patch Template. The One-derful One- Patch series of templates is perfect for making one-patch patterns and charm quilts. Each clear acrylic template is laser-cut for accuracy which gives you perfect specific-size pieces and shapes. A 1-4 inch seam allowance is already added in and there are markings for eight different sizes from 2 to 9 inches. Each package includes one template and instructions. Design: Tessellating Windmill. Made in USA.