So I recently went to a boutique where they were selling onesies like this for eighteen dollars! What? That is nuts, but I loved them. I decided I would try and make some...next I'm going to make some with ruffled bums.
To make the ruffle: I cut a piece of fabric 1 1/2"x about 17", then I stitched down the middle (don't backstitch). Pull on one of the strings to make it ruffle. Get the ruffle how you want it and pin it onto the onesie where you want it to go. (I pinned it on the seams, and in the middle). Then stitch down the seam ontop of the ruffle, then down the middle of the ruffle on the stitch that you have already stitched. This time, backstitch.
If you want to add rosettes: Make the rosettes using fabric glue, pins to hold the rosette in place and felt on the back. I waited a while and then hand stitch (or use fabric glue) to put them on the ruffle.
The final result is pure adorable....