Measure child's waist and cut elastic 2" smaller than measurement to allow for a snug fit. Sew both ends of elastic together by hand or with a sewing machine.
For a non-sew waistband, purchase stretchy headbands from your local drugstore. Most stretchy headbands come in one size so this option may not work for all waist sizes. If you're lucky, you can find stretchy headbands in childrens sizes.
If using tulle from a bolt, you will need to cut it down into 6" strips. A quick and easy way to do that is to roll the tulle into a tube... it should look like a tube of gift-wrap paper.
One end of the tulle will have a folded edge (that's how it comes from the fabric store). Starting on that edge, measure 3" and make your first cut with a great pair of fabric scissors. Then measure 6" over and cut again. Repeat every 5-6” until you have cut the entire length. You may have to adjust the strip width to make the strip width as even as possible.
If using 6" by 25-yard rolls of tulle, you won't need to cut 6" strips, since the roll already comes in a 6" width. You do have to cut each strip to your desired length. Let's say you want the tutu to be 14" long. Double that length to 28" and cut each strip to 28" long. You determine length.
Some strips might not come out completely even, but it really is okay once all strips are tied on. Any mistakes can be hidden.
Making the Skirt:
Step One: Fold your strip in half and bring it behind the elastic waistband to form a loop.
Step Two: Bring the ends of the tulle strip through the loop. Pull down the end to tighten. Make sure not to pull it too tight.
Step Three: Continue tying slipknots or regular knots around the entire waistband. You will probably use between 40-60 strips of tulle for a baby/toddler tutu. A good rule of thumb is to squeeze in at least 3 knots per inch of your waistband measurement.
And there you have your finished tutu!