I've made the jacket back rocker and oval patches with heavy twill purchased at the fabric store.
I used iron on patching material (also available at the fabric store, in larger size than knee patches) on the back.
I laid the patch pattern out in Corel, then printed it, and cut it out.
Then I fused the patching material to the twill.
Next, I used a rolling cutter (like the one the quilters use) to cut the shape. The rolling cutter give a nice, clean edge.
I then used my sewing machine to overcast the edges. You don't have to use a real dense stitch as the patching material keeps the twill from fraying.
I used the Corel document to bring the patch pattern into my digitizing software so that I would know exactly where to lay out the lettering and graphics. I also ran an outline stitch around the patch edge.
I hooped tearaway backing, let the machine stitch the outline. Then I used paper medical tape to keep the patch in place on the outline of the tearaway.
Then I let the machine stitch the lettering and/or graphic on the patch.
I hope this isn't too confusing. It really was very easy...just time consuming.