This idea is easily adaptable to make coasters, hot pads, placemats, etc., nearly anything you can think of that you would like to have a little padding underneath. Just change the size to suit your needs. I would suggest a square for coasters (maybe a 4"-5" square) and hot pads (9" square) and a large rectangle for placemats. When I make placemats, I cut my rectangles to 13" x 18" and quilt them with my walking foot after assembly. I find that placemats only really need one layer of fleece, so if you are making some, apply the fusible fleece to the back of only one of the fabrics.
I used 2 - 10" squares in the tutorial from a layer cake I had lying around, but you can use anything you want. Scraps would be a great idea. You can even piece them together and make them scrappy if you want. 2 - 10" squares will yield two mats.
Here's what you need:
2 - 5" x 10" pieces of fabric
2 - 5" x 10" pieces of fusible fleece (I like Pellon's Thermolam Plus)
all the regular necessities: rotary cutter, ruler, mat, scissors, thread, iron, and sewing machine
1. Start by cutting the 5" x 10" pieces of fabric. I used two contrasting fabrics. Note that I am starting from 2 - 10" squares and cutting them in half. I just set the extra pieces of fabric aside for future use.
2. Next, cut 2 - 5" x 10" pieces of fusible fleece.
3. Lay the wrong side of each fabric piece against the fusible side of the fleece.
4. Iron each fabric and fleece piece together.
5. Lay the two pieces right sides of fabric together and pin, leaving an opening to turn the mat right side out.
6. Stitch together, starting along one of the long sides with a 3/8" seam allowance. Pivot at each corner and backstitch at the beginning and ending of the stitching.
7. Don't forget to leave an opening!
8. Clip each corner diagonally.
9. Turn the mat right side out and press, turning in the opening edges and pressing them flat.
10. Edgestitch around the entire mat, 1/4" in from the finished edge.