Cut your waistband 10-12" longer than your actual waist measurement and 3" wide. You can use whatever fabric you like. I chose a matte swimwear knit... but it's your petticoat! do as you choose! You will also need to cut a 1" wide piece of elastic 2" shorter than your waist measurement.Sew your elastics ends together into a continuous loop.
Sew your waistband ends together into a continuous loop.
Fold the waistband in half horizontally, inserting the waistband inside the fold. Using a scant 1/4" seam allowance make a casing for the elastic. Move the excess waistband fabric around the elastic loop as you go. Be sure not to catch any elastic in the seam
At this point all of the waistband extra fabric will be pushed to one part of the elastic loop. Push around the extra fabric on the elastic and evenly distribute the excess. Now using a 1/2" seam allowance just barely catch the elastic in the seam. As your sewing you should stretch the elastic so that you have a smooth surface.
Your completed waistband should look something like this.
Attach the Waistband to the Skirt
Find all the center seams on the skirt yokes, and pin them together.
Find the center seam on your waistband and pin it to the seam on the skirt yokes. This will be the petticoats center back. As usual with fitting a gathered piece to an ungathered piece, find and match the back centers, center fronts, and the side centers and work all of the excess fabric evenly throughout the waistband. The most tricky part of this is making sure that all the layers of tricot are even and that your not leaving a bit of the skirt out. You could of course sew all three layers of tricot together, and gather them all together, but I've found that you get more volume if the layers are gathered seperately. You could also sew each layer to the waistband seperately. But, why? If you are careful, and pin heavily and watch carefully as you sew, you'll catch all the layers and your petticoat will be awesome! :) You'll use a 1/2" Seam allowance to attach the waistband to the skirts... just follow the same stitching that secures the elastic inside it's casing.
The last thing you'll do is to try the petticoat on. Make sure it fit's right before you finish off the raw edge where the waistband and skirts are attached with a serger.
It's a nice fluffy petticoat... if you would like an even fluffier one add more layers! :) Shorten the skirt by shortening the lengths of the yokes and main ruffle.
Have fun Sewing! :)
** edited to add...
If you'd like a shorter petticoat, For every inch shorter subtract 1/2" from the yokes and 1" from the main ruffle. So if you'd like a 15" petticoat, subtract 3" from the yoke and 6" from the main ruffle.**