Rulers are transparent. Whether it is light or dark, it can provide you with good vision. Made of acrylic, this quilt ruler is designed for quilting, sewing, measuring, drawing, and crafting. Please align the of the ruler with the of the map, increase left and right, find the size you need to set, cut off the excess cloth on both sides of the map along the space, then rotate the map 90 degrees, and follow the above method. Cut off excess fabric. (It can also be used to correct dimensions and make maps). The rotary cutter enters through the teardrop-shaped cut, pushing it toward the slit, or pulling it back to cut through the fabric. Fold the fabric when it is longer than 12.5 inches from top to bottom. The fold line must be placed perpendicular to the cut seam to that the cut fabric is straight when folded.