You'd need a few machine shop tools to make your own generator, as well as access to magnets and other specific materials (iron laminations, etc), as well as a

You'd need a few machine shop tools to make your own generator, as well as access to magnets and other specific materials (iron laminations, etc), as well as a good understanding of magnetics. I think you underestimate what 'world's least effecient generator' means - if energy suddenly became scarce, I wouldn't spend my time to make something that would probably make a few watts at best. Your best bet, if you really want electrical power in this scenario, is to reuse a motor or car alternator. Now the biggest issue is a source of power - unless you have access to a flowing river, you're pretty much stuck with wind. And here, you'll be limited by your ability to make efficient blades. In fact, your best power source might be you, using a bike-mounted generator. I've though about makig one for fun, but it's a lot of effort to go through, to make a device that would probably make 150W. Realistically, IMHO in this scenario I would abandon electronic devices and stick to hand tools.