This Slasdot article: http://m.slashdot.org/story/28566 http://m.slashdot.org/story/28566 describes a similar technique - glass spheres in transparent epoxy re

This Slasdot article: http://m.slashdot.org/story/28566 http://m.slashdot.org/story/28566 describes a similar technique - glass spheres in transparent epoxy resin creating an uncopyable optical fingerprint. One of the comments states that tinfoil pieces in clear epoxy photographed from several angles were used as tamper proof seals during the cold war era.