1.Cut out four rectangles from felt. This should include one of burlywood 8 centimeter (3.1 in)*13 centimeter (5.1 in), two of gray, one of black 9 centimeter (3.5 in)*13 centimeter (5.1 in) that the gray ones are a little longer than another two, one gray felt 6 centimeter (2.4 in)*13 centimeter (5.1 in) for front flap.
2. Cut out a heart shape and two wings of angle and straight stitch along the heart covering the wings to sew them with the burlywood felt.
3. Lay four pieces of felt with gray ones between burlywood one and black one.
4. Sew the edges with blanket stitch as the picture shows.
5. Link the grey front flap to the black felt by blanket stitch, covering the edge of the black felt, and stitching along the edges of front flap.
6. Look at the right side of the envelope.
7. Attach a button atop the heart in the middle.
8. Shear a small opening in place at the front flap as buttonhole.
9. Sew the edge of the buttonhole to make it neater.
10.Button up, then you can get an envelope made of felt.