Step 4: Attaching the Layers

1. Place two patchwork squares, right sides together, on top of a piece of batting. Pin in place
   
2. Sew a 1/4-inch seam around three sides of the square, leaving part of the fourth side open so you can turn the square right sides out. 
3. Trim the edges and corners of the batting before you turn it.
4. Turn the coaster right side out.