Disclaimer - I have never written a sewing or crochet tutorial in my life & have no real idea of what I am doing, but wanted to share & maybe can help someone else get extra life out of a growing child's clothing.
I decided to crochet a large bell type ruffle. I used a cotton/acrylic blend yarn & a #5 hook. I started by making a blanket stitch completely around the hem of both legs. Used embroidery floss & the stitches are roughly 1/4 inch apart. then I used a single crochet for the first round. for the rest of the legs I did half double crochet. row 2 - 5 straight stitch of one in each stitch. rows 6 - 10 are increased in 2, 1, 1 (repeat to end.) I think they came out adorable & will be easy to add on more when needed.
I decided to add a patchwork-ish panel at the bottom & then got to playing with it & thought it'd be cute to have it sandwiched between the pants & the hem. Let me tell you, this had me in a tizzy. I am an AMATEUR seamstress. & for the most part just muscle my way through stuff without knowing what the heck I am doing. But I'll give it a try. So first bit of advice is to measure a few times & with an actual tape measure (not a wooden ruler.) ( I am giving directions the way it should have been done without all the rip-outs & re-dos.) First cut off the bottom of each leg right above them hem & then use a seam ripper to take out the top stitch all the way around on both. I used a bunch of panels of cotton fabric in the same color scheme (if you can call black & white a color scheme,) all the same height. then sewed them together & pressed the seams flat. I then ironed on interfacing & sewed the whole deal into a tube. I then made another tube the same size in a lining fabric. Then I sewed them together, wrong sides together & finished the edges with a zigzag stitch. Then pin the tube to the pants leg right (outer) sides together & sew with a straight stitch followed by a zigzag to lock the edges. straighten & sew along the edge to flatten down the inside. Do the same for the cuff.
I know this is all pretty much gibberish, but if anyone out there can make this make sense, just give me a holler & go for it. Happy crafting.