There is currently only one 3D printed part on the tracer and it came from LEGO itself. (Inside Tour set)
https://library.ldraw.org/tracker/26058
This has a LEGO part number. and is a movable assembly printed in one go.
There is a second one, the toy duck, part number 92898, which was produced in a very limited quantity
For other 3D Prints, I share Orion's approach.
Some of these companies have their own library of parts they prodcue, e.g. Brickarms and Brickmania, to make their instructions, and somethimes they make these available.
https://library.ldraw.org/tracker/26058
This has a LEGO part number. and is a movable assembly printed in one go.
There is a second one, the toy duck, part number 92898, which was produced in a very limited quantity
For other 3D Prints, I share Orion's approach.
Some of these companies have their own library of parts they prodcue, e.g. Brickarms and Brickmania, to make their instructions, and somethimes they make these available.