Necessity may be the mother of inventions, but prison seems to be a particularly fertile birthing ground. Take a look at these collection of improvised tools, escape equipments and weapons made by inmates undoubtedly inspired by MacGyver.
This one to the left is the crucifix shiv:
Disguised as a wooden crucifix; found in an inmate’s cell in Wolfenbüttel prison, Germany, sometime around 1994; intended for use in an escape or as a general weapon. At that time a lot of crucifixes were fashioned in prison woodshops until jailers finally dug their true purpose.
Marc Steinmetz has the photos of what surprisingly creative inmates have made (first published in Süddeutsche Zeitung Magazin in 1999) : Link