| | Re: Elastic sides on a tshirt
Use a skinny elastic.
Start it where you want the gathering to start, put a pin in just below that to hold it in place. Cut the elastic maybe 3 inches or so shorter than the length you want to gather. Put a pin in the bottom and leave it there while you are sewing.
Stitch down the top 1/4 inch or so and lock it down with a few stitches forward and a few stitches backward. Take the top pin out but leave the bottom pin in.
Stretch the elastic as you stitch it down the center (go slow). You'll likely have to hold the top of the elastic stretched out as you sew. Keep the elastic stretched out so that the elastic stays on the seam and the shirt isn't bunching up underneath the elastic. When you get to the end just lock it down the same way you did at the top of it.
Let me know if that makes sense to you...