Years ago when I was cutting blocks for quilts I cut the left overs into 2.5",2" and 1.5' squares and threw them into their separate bags and then when I didn't have a quilt to make I used those pieces to make rugs and tops for the toilet tank.The smallest ones I used for the top of the tank and the 2.5" ones for rugs. You can use whatever you want for the backs of rugs and tank covers. I have used denim and just about anything. If you want somethin on the back of the rugs to prevent them from slipping sew that on first. Fold your squares in half and start in the middle and leave the same amount of space on either end make a turn and come back up one side of your first strip and go back down the other side . Keep doing this until you have the whole piece covered. I'll try to post a picture of the tank cover.