I made fabric covered boxes years ago. I used fusable web to adhere the fabric to the boxes. Cut the fabric to size and iron on the boxes. If doing round boxes trace around the round top, bottom add an inch all the way around. Snip around the circle of fabric 1 (one) inch in and 1 (one) inch apart, iron on fabric add the side fabric that you measured around the box adding an inch to length. I used tims around the bottom and top edges. I have no pattern, I just looked at the boxes and tackled the problem. Sorry no sewing involved.