He makes great projects!
I have always kind of wanted a giant Fresnel lens for a solar scorcher:
I always wonder what you could do with a solar scorcher. Turn random hydrocarbons into charcoal?
Melt metal?!
I'm sure you could melt metal, if it is thin enough, one point at a time.
That would be an interesting proof-of-concept, but I can't imagine trying to melt scrap sheet metal.
You know, if you could melt metal, making charcoal might be difficult, since you could burn through the container!