Computing
- One could create a list of levels for building a computer, the lowest ones being the hardest yet the most self-sufficient, while the higher ones being easier but depending on a global supply chain and pre-made components. For simplicity, on lower levels this list uses triodes (you can also probably use relays, but prepare to get a very slow computer) due to relative ease of fabrication, and on higher levels it uses transistors because they are very cheap.
- Finding the metal deposits yourself, mining, making wires, vacuum pumps, glassblowing, soldering and welding equipment. Making some triodes. Assembling a computer out of DIY triodes.
- Same as (1), but buy all or most of the materials and equipment for making your triodes instead of making them yourself.
- Buying (or salvaging) thousands of extremely cheap transistors and building a computer out of them.
- Building a computer with 74xx series chips.
- Soldering together a computer with IC components like microprocessors, RAM and ROM chips, etc. Might mostly work with some microcontrollers or old chips (good luck trying to reuse the mess that is the chips of a modern smartphone. Figuring out their workings will take time).
- Putting together a modern computer the architecture of which descends from IBM PC. Easy like legos.
- Using an existing computer, old or new, and modifying it for your needs and desires, whether physically or programmatically.
