Here in Texas a prison inmate (low security prison) cut his way through the bars of his cell using dental floss coated with sand. It took a while but the cuts were so thin as to be unnoticable.

The jade carvers in China use a similar technique. They coat a fine, strong thread in sand and slowly wear there way through the jade.

Something to consider.

-Blast

link to prison break story (towards end of article)