My new serger needed a dust cover. I could have bought a plastic one, but they rip easily. A fabric one is also much cuter.
I used about 7/8 yard of a calico print and cut out 4 pieces.
I got the dimensions of my serger with the spool stand in the 'down' position. My machine is 13" wide, 11" deep and 11" tall. I added 1/4" seam allowances and made 2 side pieces that curve on the side, and rectangular front and back pieces.
Sewing the cover was a piece of cake with the overlock machine. It took about 10 minutes, was all, and the fabric was just $3. This is a super simple dust cover. If you decide to make your own, you could also back the fabric with interfacing to make it stiffer or use upholstery fabric, add a pocket on the side for accessories or finish the edges with bias tape.