There is a few services out on the web where you can submit a file and someone in the community with a 3d printer can print it for you, think of ride sharing except with 3d printers!
One problem with this though is it’s almost entirely a manual process.
You place your order, the website processes it, the person with the printer gets the file, at their earliest convenience they start the print, once they realise it’s complete they let you know.
I believe a number of parts of this process could easily be automated.
First comes octoprint, it can run on a raspberry pi and connects the printer to the internet.
Utilising the API the online service could automatically send the print job to the printer.
This is the first hurdle, the job can now be sent to the printer automatically, negating the need for the owner to load the file and start the print.
This isn’t perfect, what if the incorrect filament was loaded? Running out? Or just plain you wanted it resized?
There’s sensors you could integrate for the first two, and you could pre splice your model if you wanted it resized.
Note what if there was already a model on the print bed?
You could sense that somehow too, my first choice would be machine vision to check if there is anything there that isn’t normally. I think this would be the most accurate.
But you could accomplish this with a much cheaper and simpler sensor like a proximity sensor, or a rangefinder going over the bed level.
The octoprint API again would be able to stream you a live stream of the print, and when its finished it could send the online service a trigger that the print is finished, along with a photo of the completed print the moment it was finished printing.
It could even go as far as sending the recorded time lapse over to YouTube and linking it in the completed email!
This would let the user review the print and check for defects / print problems to some degree, so they could instantly email the printer owner if something went wrong and request a re print.
This could save a lot of time and speed up the process.