Answer: Atoms of solids such as iron or stone hold each other very well. Together they form a kind of chicken wire. Anything larger than the holes in the mesh cannot fall through.
Answer: To start with the latter, that's what people thought 100 years ago too! Back then there was no computer, no television, no cell phone and so on. Yet people thought there was nothing left to invent. So an inventor does not have to worry about whether something has already been invented or not. There is always a lot to discover. How? Start small, with the things you find fun or mysterious. And when you make something, think whether you can come up with nice changes or improvements yourself. Be curious and not afraid to make mistakes.
Answer: The prints can soon be ordered from Eurocircuits, follow the news section on the site.
Answer: an electron has no legs and therefore cannot really run at all. But when you apply voltage to a conductor, the electrons jump from one atom to the next. It seems as if they are running through the guide.