Select a piece of fabric.  Because you will be sewing through two layers of stabilizer, cardstock, and fabric, be sure that the fabric is thin and flimsy.

Apply a lengthy spray of adhesive to a piece of cutaway stabilizer.

Press the fabric onto the stabilizer, smoothing any wrinkles.

Turn the fabric/stabilizer composite over so that the fabric is face down.  Take the card, and trace the outline of the card onto the stabilizer.

After the outline is drawn, make 1/4 to 1/2 inch in from all sides.

Connect the marks...

Using either straight or decorative scissors, cut along the drawn lines.  The result will be a fabric/stabilizer composite that is 1/4 to 1/2 inch smaller than the card.

Spray the stabilizer side of the composite with spray adhesive.

Press the fabric/stabilizer composite onto the card.

Spray the inside flap of the card with spray adhesive.

Hoop a piece of cutaway stabilizer, and press the sticky-side of the card onto the stabilizer.

Embroider the design.  Any design that has the word 'cardstock' in the name, any design that is shaped for a card, or any sheer design can be sewn using this technique.

Cut away the excess stabilizer.

The inside of the card will show the back of the embroidery and the stabilizer.  You can cover this with a decorative sheet of paper.

Write a personal message, and mail the card.  The recipient is sure to treasure this unique greeting.