This is a simple jersey tunic with an added ruffle collar. I used about 1/2 yard of purchased jersey, but you could also recycle an XL tshirt.
First, find a tshirt that fits your little one and fold it in half. Place the fold of the tshirt on the fold of your fabric (you will need two of these so my fabric is doubled over). See how I've angled my folded tshirt at the bottom (in other words, the bottom of the tshirt is not snug to the fold)? That will allow me to cut an aline shape rather than a straight sided shirt.
Cut around the shape of the tshirt as I have shown. My tshirt had short sleeves. I have added some length to my cut fabric at the sleeves as I want them to be elbow length. My neckline is also cut slightly larger than the tshirt. The strip along the top is about 3 inches wide. This is the strip I will use to make the ruffle. If you are recycling an XL tshirt, you may have to cut out two of these strips and sew them together to make one long one. If you have folded over a length of fabric as I have, you should have enough.
When you open up your fabric, you will have two identical shirt pieces and one long strip. Don't be alarmed that your cut fabric is larger than your original tshirt because we are going to sew up the seams and add a pleat or two at the neckline which will make the finished garment smaller.
With the good sides of your fabric together, sew the shoulder seams and the underarm and side seams (shown below). If you are using a serger, remember to finish your "tails" so that they won't unravel because the cuffs and hem of this tunic will be left raw. If you are using a regular sewing machine, simply backstitch at the beginning and end.
Neckline looks too big right? Add a simple pleat at the centre front of the shirt. Eyeball the neckline. Is it still too wide for your little one's shoulders? If so, add another one at the centre back as well. (Don't worry if it's still too big. I'll tell you a trick for making it a bit smaller when the whole shirt is constructed). You have the choice of turning the neckline under here for a more finished look, or just leaving it raw. If you choose to leave it raw, please stay-stitch it (a straight stitch all the way around to prevent it from stretching out too much) as the weight of the ruffle will stretch the raw edge over time.
Now the fun ruffly part: set your machine to the do the gathering for you. Most machines require you to set your stitch to it's longest possible length and the adjust the tension to tight-tight. (If your thread breaks, it is too tight so loosen it a bit). Simply feed your long strip of fabric through the machine this way and the jersey will gather for you. Leave long tails at the beginning and end so you can adjust the ruffle to shorten/lengthen it.
Nearly done! Lay the ruffle around the neckline of the shirt and adjust the length as necessary. I made two versions of the neckline. My favorite is where the ends meet at the chest (coming down the front chest a couple of inches and hiding the pleat). My other version simply goes all the way around the neck, meeting up at the front. Pin into place if you desire then stitch to the tunic about and inch below the neckline edge. This allows the top half of the ruffle to fold down and expose the neckline.
If you think your neckline still needs to be smaller, you can cut 5 inches of elastic and stretch it as you sew it into place either under the ruffle at the back or at each shoulder. This will cause the area to gather with help from the elastic. Done! I left the cuffs and hem raw (jersey does not unravel like cotton does) and they roll up a little in the wash. I'm really happy with this tunic. I think my closet needs one now...