Take your time making the template. It's easier (and less expensive) to adjust that than to cut another piece of fabric.
- Paper lampshade in white
- Large sheet of paper, such as a double page of newspaper
- Cotton fabric
- Sewing machine and sewing supplies
- Double-fold bias tape
- Fabric glue
To make a template, place shade on its side on paper. Roll shade slowly, tracing along its upper and lower edges. Continue tracing all the way around the shade.
Add 1/2-inch seam allowance, and cut out. Place paper template on fabric, and cut fabric.
Sew fabric's short, straight ends together, and press seam open. Turn right side out.
Slip fabric over lampshade. Cut lengths of bias tape to fit around the top and bottom (allow 1 inch extra, for overlap). Slide bias tape over shade's top rim. The front half should cover the fabric; the back half should cover the inside of the shade. Squeeze a thin line of glue around the shade's inside and outside, and pinch along tape to adhere bias tape. Repeat with bottom rim. Let dry.