Disrupt the product differentiation rut that the shoe industry is stuck in with modular shoes.
Build the base, with a layer of padding (that over time conforms to the shape of your foot). Make this part Birkenstock-comfy (though thinner).
Then, unleash upon the world a long tail of options you can swap out at any time, depending on your requirements and aesthetic. New covers, heels, become a sneaker, or formal wear. Running would be a specialized function, but sliding in a steel tongue for boots is not a big deal. Make each one of these options $5/$10 and enable them to be locally produced (you earn royalties on the plans).
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