You will need:
--cotton fabric with a small print (choose this carefully as it will be the center of attention!)
--Heat n Bond Lite, or other two-sided, fusible interfacing that you can sew through
--heavy sew-in interfacing
--sewing thread and needle
--heart templates (at the end of this post)--they work best if you trace them onto plastic and cut them out. You may need to/want to resize the templates when you print them out. The large one is 2 5/8" wide and 2 3/4" tall. The smaller one is 2 1/2" wide and 2 3/8" tall.
Start by tracing the smaller heart onto the smooth side of the Heat n Bond. Cut it out, just outside the line, and iron it onto the cotton fabric. When it is cool, cut out the heart on the drawn line (this cut doesn't have to look perfect because the edge will be hidden under the felt).
Still using the small template, trace and cut out 2 hearts from the heavy interfacing. (I used two interfacing hearts for added firmness in my finished keychain.)
Next, cut a strip of your cotton fabric 2" x 3 1/2" for the key fob.
Iron the strip in half lengthwise, then fold each side in to the center crease, and press.
Sew the open side shut. Don't bother to sew the ends, because they will be covered.
Slip the keyring onto the fabric and fold the strip in half. Baste the ends together. Set aside.
Next, using the larger heart template, trace three hearts onto the felt. A ballpoint pen works great for this. Only one of the hearts needs to have the center heart drawn onto it.
Cut out the three felt hearts. Now all your pieces are ready to assemble into a beautiful keychain!
Remove the paper from the back of the fabric heart, and iron it onto one of the solid wool hearts. Then position the keyring fob behind this heart, leaving about 1/2"-3/4" of the fob exposed, and sew firmly into place. Remember to only sew in the area that will be covered by the heart with the "window" cut out of it.
Here's the back. You can trim the cotton fabric to within 1/4" of where you sewed it to the felt heart, if you wish.
Next, layer the two interfacing hearts under the wool heart, and lay the cut-out wool heart over the fabric heart.
Baste the layers together. The red basting stitches will be removed, so they can be big and sloppy!
This is what the back looks like. (The heart on the left is the piece that will cover the interfacing after a few more steps.)
Using a blanket stitch, sew around the inner heart with the embroidery thread.
This is what the back looks like. Now, remove these basting stitches.
Here's the last step: with the third felt heart layered onto the back, baste all the layers together, then embroider around the outside edge with a blanket stitch. (There are lots of places online that explain the blanket stitch, like this one at Stitch School.)
Remove the basting stitches, and you are done. Looks great!!
The back looks great too!