Melt them down with solvents/heat and then cast them into something useful. Every home could have its own artisanal plastic forge. It could be the Great Leap Forward (Third Five Year Plan).
Some chirugs will do a test run on a printed hearth before they do it on a patient (they actually scan how the hearth looks like in the patient and model after it), protheses are being printed to custom fit per patient,...
Yes, home printers are still very into novelties and arts. But for custom parts 3D printing is very common.
As soon as mass production starts then yes, other techniques are much faster.