Finely divided iron and aluminium not available in your jurisdiction?
The bars of your cell are iron (based) and you can find aluminium (based) items in the kitchen. An edge of your stainless steel furniture can be used to create scrapings.
Always check with your Warden before trying this in your own cell block.
Outside of the jurisdiction of your typical prison compounds, the materials are not restricted.
Note: The iron and aluminum do not have to be finely divided if you have a hot enough flame to ignite the combination:
http://en.wikipedia.org/wiki/File:US...ion_damage.jpg