Hi Kate2. Welcome from oh boy it is cold outside here in Michigan. Great weather for quilting.
You can buy Moleskin at the drugstore, or in the health and beauty aids section of a department store. It is the stuff our grandmothers, moms and maybe now even us use to pad corns on their feet. It is in the Dr. Scholl section, or ask at the pharmacy. It is pinkish color. I prefer it to mark my 1/4" line.
Linda