Designing the layout of the PCB. Populating it with surface-mount components using home-made solder paste stencils and an oven. Selecting the MCU. Figuring out what kernel drivers are needed and what can be stripped out. Searching the web for datasheets and drivers that others have created/ported. Building the userland. Debugging and testing.
Like many pieces of technology, once you lay out the steps it starts to look as though each one, and therefore the whole, are achievable to a highly-motivated but somewhat typical person. And it's true! But even so, few people develop the whole set of skills to build something from start to finish, even notwithstanding the incredible help you can get nowadays from open-source software, consumer access to services such as PCB manufacturing, and online documentation. Even in a high-achieving community focused on building stuff, like this one, I doubt many posters here have completed as impressive an individual project.
Like many pieces of technology, once you lay out the steps it starts to look as though each one, and therefore the whole, are achievable to a highly-motivated but somewhat typical person. And it's true! But even so, few people develop the whole set of skills to build something from start to finish, even notwithstanding the incredible help you can get nowadays from open-source software, consumer access to services such as PCB manufacturing, and online documentation. Even in a high-achieving community focused on building stuff, like this one, I doubt many posters here have completed as impressive an individual project.