In the eighties having circular floor length table cloths for 24" diameter occasional tables was on trend. I thought one either end of the sofa would look great so bought some sheeting to get the width to cut the circles and set about sewing with the scallop satin stitch around the edge. My old Elna coped better if I stayed 1/2" in from the edge; so far so good. The mathematicians amongst you will be able to work out how much trimming next to scallops with embroidery scissors was needed. Oh the blisters. . . . I didn't ever do that again!!!
Currently I play with all the stitches when I make zippy pouches. I use batting to give the pouch a bit of structure and a few lines of fancy stitching in a matching thread adds a little something.