I love these onesies for baby gifts, but you could use the same instructions to decorate a kids' tee, apron, book bag, etc. Be creative! Have fun!

A super-fun (but more complicated) option is to design your child's initial surrounded by a shield in the shape of a Superman S. In red and yellow, of course.

Materials:
Fun fabric (prewashed and ironed calico for best results)
Coordinating thread
Cotton onesie or tee shirt (prewashed for best results)
Paper-backed fusible adhesive ("Wonder Under")
Fabric stabilizer (it's like very heavy interfacing)
Iron & ironing board
Sewing machine
Scissors
Pencil & paper

Optional:
Computer and printer
Rotary cutter, ruler and cutting board

Step 1: Make a Pattern

Use a computer and printer to make a letter pattern, or free-hand your own. For a small onesie, I like a letter that is about 4 inches tall and 3 inches wide. Tip: use the outline option on the font to avoid wasting ink. After printing my pattern, I changed the shape a little to further personalize it. Cut out the letter.

Step 2: Prep Your Letter

Place the letter face-down onto the Wonder Under and trace around it with the pencil. Important: Make sure the letter is backwards at this point, and that you are tracing the letter onto the paper backing side of the Wonder Under. Now cut the Wonder Under out around the letter (outside the lines).

Step 3: Iron the Wonder Under Pattern to the Fabric

Iron the Wonder Under letter onto the back of the fabric, following the manufacturer's instructions (you will be using a damp press cloth, as shown below). Cut the paper and fabric, this time following the outline of the letter. Peel off the paper backing and iron the letter onto the onesie, again following the manufacturer's instructions.

Step 4: Cut Fabric Stabilizer to Size

Cut a piece of fabric stabilizer bigger than the size of the letter and position it on the inside of the shirt. In the pic below, it's shown on the outside of the shirt, but that's for size purposes. Go ahead and slip it inside.

Step 5: Sew Around the Letter

Use a zig-zag stitch with a very short stitch length and pretty wide stitch width to sew around the edges of the letter. I go over the whole thing twice, the second time at a slightly wider stitch width to cover any bare spots in the stitching.

Take your time. This is the slowest part of the whole process. Be careful to open the onesie and only sew through one layer of onesie fabric, the letter fabric and the stabilizer.

Trim the fabric stabilizer as needed.

Give it a final press and slip it over the head of the intended recipient. Fun!!

Step 6: Optional: Ruffles

Using the rotary cutter, ruler and board, cut three bias strips of fabric, each one 7/8 of an inch wide by about 16 inches long. Trim one so it is about 15 inches long, and one so it is 14 inches long.

Step 7: Ruffles, Continued

Round the edges of the pieces. Using the sewing machine, sew a basting stitch (the longest straight stitch possible on your machine) through the middle of each strip. Leave long ends of thread. Pull the bobbin (wrong side) threads to gather the pieces.

Step 8: Ruffles, Done

Use pins to arrange these gathers on the bottom end of the onesie. Put the longest one on top and the shortest one on the bottom. I put mine about an inch apart. Sew through the middle of each gather using a straight stitch designed for stretch fabrics. Be careful to open the onesie and only sew through one layer of onesie fabric. Pull out the basting stitches carefully.

Don't worry too much about perfection on this step. After you wash and dry the onesie, these little ruffles will fluff up sweetly.