What I'm wondering now though is how much flexibility the FAA and courts have in charging/sentencing people with that registration offence. I'd hate to think people could be going to prison because they forgot to file some paperwork on time.
As interesting as your solar smelting idea is, unless the focal point covers the entire mass to be smelted it won't matter. For that you would need an array somewhat larger than this one https://www.youtube.com/watch?...
And though in theory you could build a movable support structure for the mirrors from wood, maybe, you won't have the precision tools to make mirrors of a high enough quality to do the job. Even if you could, you would need a lot of those arrays to smelt on the required scale, and then you need to keep the metal uniformly hot to work it. A solvable engineering problem, but quite a hurdle without metal. You need metal to make tools to make higher grade metals to make higher quality tools to make everything else. You're going to have to burn something to get started.
So, no fossil fuels limits metallurgy to what you can melt with a wood burning furnace. And if what the poster means by "fossil fuels" is actually any carbon producing energy source, wood is out too.
"Our experience is [piracy] leads to more penetration, more paying subs, more health for HBO, less reliance on having to do paid advertising If you go around the world, I think you're right, Game of Thrones is the most pirated show in the world. Well, you know, that's better than an Emmy."
If that view was more widespread, we wouldn't have to deal with DRM that only interferes with paying users.