Wow, that's a lot of work for one little cap. But yes I agree this is a great use of 3D printing. I have already used it successfully too to replace caps for things like USB sticks, kitchen items, or some broken plastic mechanical components that you just can't reorder separately. There needs to be a service to support this use of 3d printing if it isn't there yet. An online database just for replacement parts, where people can sell their models for small fees. It would list all items in a thoroughly categorized way, and it should also have a section with requests so people can ask modelers to create parts to add to the database.