That's hardly from scratch, though. Just look at all the different tools he uses. We didn't even have glasswork precise enough to use until the 18th century. Add arc welders, all of the chemicals (and chemistry, mining, etc) needed to make filaments, and everything else required and I doubt a person with full knowledge and access to all of the base materials, as they exist in nature, would be able to build a computer in their lifetime.
> full knowledge and access to all of the base materials, as they exist in nature, would be able to build a computer in their lifetime.
Even that's a huge head start over having to mine the raw materials.
It would probably take several lifetimes to build even the most basic computer from complete scratch even with all the manufacturing knowledge available.
