Do you have a LQS or Walmart? I take it you are new to quilting since you ask where to buy basic quilt supplies. If you have a Joanns or Hancocks in your area they would probably have the best selection. Even the best of tools do not produce exact measurements unless you use them correctly. :lol: I didn't mean to thwart your efforts; perhaps I misunderstood your basic question. Accept my apologies if I did. Remember, there are NO stupid questions here. ;-)