so. here's the deal:find a skirt that's too small and get some dark knit material a little longer than the length of your skirt that matches. (black, navy blue, dark brown, or even deep purple would all work awesome)
then cut off the side seams plus a little bit (i'll give you a hint, i didn't cut off enough and had to make up for it later also... make sure to cut so that it leaves the right curves of a pencil skirt... the cut shouldn't be a straight line)
cut your dark knit material to fit you will want at least 3 inches wide in order to get the right effect. (my strips are 4 inches)
then pin and sew your strips into the skirt making sure to fold over the top and bottom to make a "kinda" waistband and room for a hem on bottom. do this on both sides
hem around the bottom
then cut off your corners -without cutting your stitch so that you won't see the gross inseam when it's flipped right side out (if you use a serger this step would be removed)
I really really love this skirt. it's super slimming because the eye is tricked by the dark stripes on the side. 4 whole inches get visually removed from my body. the knit material makes it so that it will stretch and grow with me incase i grow. and... it's actually way more comfy and easy to walk in because of the knit black material.