Not exactly cheap, but designed to be durable and require only a decent microscope to read:<p><a href="http:&#x2F;&#x2F;rosettaproject.org&#x2F;disk&#x2F;concept&#x2F;" rel="nofollow">http:&#x2F;&#x2F;rosettaproject.org&#x2F;disk&#x2F;concept&#x2F;</a>