I've been planning to make a sewing machine cover for a long time. My work horse is a commercial grade Singer that's as basic as you can get--this side of the beautiful Singer antiques. Reverse, zig-zag, blind stitch, button holes - that kind of machine. And the needle threads front to back. What else?!
When I finally decided to just make a cover right now, I figured I didn't need a pattern, just a few measurements.
I used a ruler and found that front, top and back measured about 24 inches, with the width coming in at 19 inches. I also found that the side dimensions were basically 8.5 inches by 11 inches, which is the size of regular paper. So I took a piece of ruled paper and rounded off the top edges, to get a gentle curve to attach to the main piece that goes over the machine. See my little schematic below. It's not astrophysics!
Fast, easy, and no pattern. And now, no more dust on my sewing machine. A perfect AM project.