It is especially helpful if you have multiple tubes to turn, like in this sailor's knot headband I made for my niece.
First off, it is a technique that uses an overcast serger. So, if you don't have one, it is just one more reason to add a serger to your wish list.
You'll need a serger, and a large eyed needle. That's it.
To sew your tube, you'll serge over the raw edges, with your right sides of your fabric facing each other. You want to make sure that you leave a long chain on the end of your strap. I'd recommend a chain that is at least six inches.
I used a basic three thread overcast stitch. A four thread would work as well.
Once you've overcast your edges, thread your chain into the eye of your needle.
Insert the needle into the tube (same end as the threaded chain). Feed the needle/chain through the entire length of the strap.
As you gently feed the needle/chain through, the tube will turn right side out. Easy as that.
In no time you can sew up several straps for your summer sundresses.