You really need strong Sun screen

[Pat K]

http://www.wimp.com/meltsrock/

[KBCraig]

Uh oh. Jim may have found a new project.

[dalebert]

I was able to write on wood with fire using a foot-wide Fresnel lens.

[Jim Johnson]

In 1969 my friends and I built parabolic reflectors out of card board and tin foil.  We had heard that this was the thing that was going to solve the energy problems for poor people in India.
Today I pity all of those poor, burned and blind Indian people.