Fimo is a kind of polymer clay and in the polymer clay and glass world a cane is a rod made of fine strands of color arranged so when the rod is sliced a picture or pattern is exposed (plus other things in glass) So you get a cane and slice thin pieces off and then apply or roll those into the fingernail or other craft you were making. They work fine with a little care to not distort them.
Got this off yahoo answers. Thx and good luck of you bid:)