From my comment on this question/answer Why wasn't Superman naked when he was lifting Luthor's artificial continent?
Supposedly the blanket is made of a super strong fabric, which is why it can withstand so much abuse; but if the material is so durable, how was Martha Kent able to tailor it into a form fitting costume?
Martha Kent unwove the Kryptonian fabric and rewove it into his costume. It was indestructible, didn't get dirty or torn and neither did his cape. She also created the S-shield.
Wouldn't her scissors break (or her hand) from the effort of trying to cut/tear/disassemble it?