Draft a Fast and Easy Flounce !
It is a variation of an Ottobre Design pattern (from issue 4-2006, #25),
and the pattern already included pieces for the flounces.
I'll be using a sleeve pattern that includes seam allowances in this example of how to draft a flounce. First, make a copy of the sleeve pattern to which you will be adding the flounce. Next decide how wide you want the flounce to be, and shorten the pattern from the bottom by that amount then ADD on a 1/4-inch. This extra 1/4-inch is what you'll need to sew the flounce to the bottom of the sleeve. Now, using the newly shortened bottom of the sleeve as a guide, draw a simple rectangle that measures the length of the sleeve bottom by the width of the flounce you want PLUS a 1/2-inch (This rectangle will become your flounce pattern after some manipulation). Again, this extra 1/2-inch is what you'll need to sew the flounce to the sleeve with 1/4-inch left-over to hem the flounce itself. The photo below shows these steps already completed. It may sound a little complicated, but all that's been done so far is to...
Shorten the sleeve length and add a seam allowance to it. Make a rectangle and add a seam and hem allowance to it.