Both of these projects use left over polyester batting. The first is for your bigger pieces.
1. Fusible interfacing for bags, pouches, and other projects.
I use quilt batting in all of my regular zipper pouches to make them more sturdy. First cut a piece the same size as your fabric piece. Place it under your fabric with the right side facing up. Starting in the middle, press down, and slowly move to each side. The batting will become thinner and sturdier the more you press it. If it starts to stick out from under the edge of your fabric, don't worry, you'll trim it down after you press. When you're finished pressing, the batting should be stuck to the backside of your fabric! Sew it as you normally would.
The smaller scraps of batting can be pulled apart and used as stuffing. Just keep tearing the layers into smaller and smaller pieces until it is similar to polyfil. You can use it to stuff toys, pincushions, whatever!