Feel free to use my idea. The general measurement whatever you want. The pictured one is white strips for the top half cut 1 1/2" wide and 2 1/2" wide. the black keys are all 1 1/2" wide. All are 8" long. assemble referring to the picture. Use 1/4" seams. After you piece the top part of the keyboard. Sew a strip 8" wide by width of your key board for the lower part. if you stayed straight on your seams you can sew 1" apart starting at the bottom of the white keys as with a normal keyboard you will come out off center at the bottom of the black keys, but should come out even between the black keys on the 2 1/2" white strips. I used a poly batting and just muslin for the backing. Quilted it on my longarm, but use a walking foot if you do it on your home machine and allow several inches extra for the take up if trying to make it fit a cornice or keyboard. Feel free to ask any questions, I'll help if I can.