He choosed a very complicated way to just build a solar oven ("four solaire" in french).
http://www.google.com/images?q=four+solaire
http://www.google.com/images?q=solar+oven

Reading the new, I thought I will see a fool building a new solar plant in his garden... Like (in smaller size) the one in Spain (PS10), or the one in france (Odeillo).
http://www.ecosources.info/images/energie_industrie/Tour-solaire-concentration-PS10.jpg
http://www.heliome-solaire.fr/l_energie-solaire/utiliser-l_energie-solaire/four-solaire-odeillo.jpg

Note: if its just to burn some stuff, my chidren use a magnifying glass and its enough.

We have a producer in France (MDI), which build "CAT" engines and cars.

See http://www.mdi.lu/

Some medical devices used Magneto-Optical media for recording huge data examination.
But... builder for media and reader said it will stop this technology (too old).

So, how long will we have de devices to read all these media ?
How long will they produce the media to fill in still running devices ?

A study for archiving nuclear location informations conclued that the better solution was... paper (not common paper, but paper with just printed and eye readable informations).