I think I started making these when Lucy was 4. She likes the number on the front and for it to come with a matching skirt. Some years I've made the skirt, some years just bought something matching (based on my busyness level). Jack likes a J on the front and his number on the back. Most birthday eve nights you'll find me frantically sewing at 11:00 pm.
Sometimes the kids pick out the fabric, sometimes I just use what I have. Asyou can see in Lucy's 4yo picture I started doing regular applique, but then I found out about reverse applique. It is so easy I've used it for just about every applique project since.
Freezer Paper - found at larger grocery stores and big box stores
fabric for applique
plain t shirt
iron and sewing machine
Find a font you like and print out your letters/numbers in the size you want. As you see, I am running out of printer ink at almost all times. Not sure how this is possible. When choosing your fabric, think about how much of it will actually end up showing and don't get something with too large of a print.
Cut out the number/letter (use are going to use it as a trace around pattern) and cut out a chunk of fabric with room to overhang.
Turn the shirt inside out and decide if you are doing the front or back of the shirt. Place the fabric face down on the shirt, centering where you want the number/letter to end up. So at this point, the right side of your fabric should be touching the wrong side of your t shirt.
Cut a piece of freezer paper large enough to overlap your fabric piece by about 2 inches around. Place the freezer paper shiny side down onto the fabric. Using a dry and hot iron, iron the freezer paper onto the fabric t-shirt sandwich. Let it cool a bit then take your number/letter pattern and trace it onto the freezer paper, making sure it is where you want it to be on the shirt. **Take note you have to trace it in reverse as you see above.** Check the seal of your freezer paper, it should be pretty well stuck.
Now, time to sew. I usually use a contrasting thread as I like how it shows up on the front. I use a straight stitch set at about a "2" length. Remember to take care so that you don't sew through more than one layer of the t shirt. Sometimes I have to sew in reverse to get to all the spots of the number/letter.
When you've finished sewing, rip away all the paper.
Use pinking shears to trim away the excess fabric. The turn the shirt right side out.
Ooops. Forgot to stitch the middle of the nine the first time around. Better go fix that.
Now it is time to trim out the t shirt fabric. My first inclination is to trim out the middle hole of the 9, but any fabric in the middle of a letter or number needs to stay to make it work. What I want to do is trim out the actual body of the number/letter. Pinch up so you have just the t shirt fabric in your fingers and none of the applique fabric. Start cutting.
As you're trimming, you'll want to leave a little edge of t shirt fabric along the sewing line. After washing a few times this will curl back a bit, but it won't fray. Now just repeat if you want to add something to the other side of the shirt. I've used this method for many shirts besides birthday ones. It is a easy way to add a little fun to plain shirts, especially when you are sick of every kid's shirt in the stores being covered with branding or screen graphics.
Brace yourself for Jack's favorite teenager pose.