Supplies for a Toddler-sized costume:
-1 yard of very heavyweight Pellon/interfacing--mine was a little less than a yard (31") because it was a remnant.
-1 square of craft felt in red
-velcro (I prefer sew-on, but I guess you could also use iron-on)
-toddler-sized t-shirt (for measuring purposes)
Press any wrinkles out of your interfacing and cut it in half, creating two rectangles and stack them. Measure the length and width of your rectangle and write down your measurements. To create the "print" on the card face, I found an illustration of the 2 of hearts online and put it in Microsoft Publisher to make it the correct size for the costume.
Open a new document in Publisher and choose 8.5" x 11" portrait size. You will need to resize your page to the measurements that you took and wrote down.
Under the "Page Design" tab, select the drop-down menu under "size" and click "Create New Page Size" toward the bottom of the menu:
Adjust the settings on "width" and "height" to reflect your own measurements.
Insert the picture that you chose and re-size the image to fit your page.
Crop the image in half, top to bottom.
Crop the image in half again, side-to-side, so you only have about a quarter left (this is not an exact measurement, just make sure all of your design is included in this crop). Copy this image to the clipboard.
Open a new 8.5" x 11" document and paste your image from the clipboard into your new document. DO NOT re-size to fit this page. Your pasted image should reflect the measurements from your other document. Print this image.
Okay, now you're ready to cut out your lettering. My image also had a rounded corner which I cut on the paper and transferred to the fabric to give a more authentic playing card look. When cutting my hearts and the 2, I did so in a manner that would allow me to use the remaining paper as a template for later placement, like so:
Take your toddler's t-shirt and place it on top of one of the interfacing rectangles, marking where the sleeve meets the edge of the rectangle. Below the lower mark is where your Velcro will start (where the tape measure is pinned). Above this mark is where you will stitch the shoulder seam.
Cut your Velcro to length, beginning at the "below-sleeve" mark and ending about 1" - 2" from the bottom (see photo above). Using the zigzag setting on your machine (3rd from left in pic), stitch the Velcro in place along the sides..
Velcro the front and back sections together and, using a straight stitch, stitch two shoulder seams around the top curve or corners (depending on your style choice) of the rectangle.
Take some cardboard (I used two box flaps) and place between your front and back pieces, underneath where you want to place your felt design. Using your template from earlier, place on the corner of front piece:
Apply felt glue to the back of each piece on your design and place in the template. Repeat this step on the opposite (diagonal) corner. Allow to dry for a few hours.
It's a minor miracle that he stood still for that photo! After the first wearing, I cut a shallow neckline into the front piece for more comfort. My son, who is 22 months, did manage to get it dirty in a few places. If you need to wash it, I recommend spot cleaning. Otherwise, if you need to get a bit more thorough, you may wash it in the washing machine on "delicate" and hang it to dry. HOWEVER, the felt glue is a little water-soluble. I did face the issue of losing a couple of felt pieces off the thing, but I was easily able to re-glue them before the next wearing with no problems. The interfacing holds up well in the wash cycle. You can avoid losing the felt shapes by topstitching them on with red thread, but that betrays the "quick and easy" nature of this costume. :)
Sew on, sew until your dreams come true!