The coaster is 10 inches square.
Out of some patterned fabric you will need
1 piece 4 1/2 inches x 2 1/2 inches
1 piece 6 1/2 inches x 2 1/2 inches.
I used linen for the other pieces and you will need
3 pieces 2 1/2 inches x 2 1/2 inches
1 piece 10 1/2 inches x 2 1/2 inches
2 pieces 6 1/2 inches x 4 1/2 inches.
Arrange them as follows and sew together. I sewed the 2 1/2 inch squares to the patterned fabric first and then the big rectangles to the bottom of the T. You should have 3 pieces now that can be just sewn together.
Cut out some batting (I used wool) and some backing fabric about 12 inches square. Layer them and pin to hold them in place.
I used 2 strands of embroidery cotton to sew around the T to hold all the layers in place.
I cut about some binding 2 1/2 inches wide and think I used about 50 inches. I cut across the width of some fabric which was only 42 inches wide and then cut an extra 8 inches or so and sewed the two pieces together. Fold it in half lengthwise and iron and then attach to the front of the coaster right sides together mitring the corners. Fold to the back and hand stitch in place.