Next you will rip a piece to make the piping. Now generally, you use a bias cut piece for piping, but I’ve found for these little projects, and edge piece works just fine.
If you are doing ruffles or pleats, you will also need to rip a piece for that. Figure out how long you want your ruffle/pleat to be, add 1.5 inch for the hem & seam allowance & rip another piece.
So you should end up with some ripped pieces for the pleat/ruffle and to make the piping. Put those aside for now and cut a piece of fabric to cover the chair cushion.