Finally, a subject on Motobrick that I'm knowledgeable about....3D printing!
There are metal 3D printers, you'll get parts slightly lower than cast strength but probably in a usable range for this application.
Most 3D printers print in plastic, some are pretty strong, it depends on the printing technology, part orientation, material, etc.
We have a 3D printer at work that prints a combination of plastic and carbon fiber, almost as strong as aluminum.....but only in the direction of the carbon fibers!
The first thing you'll need to do is find or create a CAD model of the part so you can output the STL file needed for printing.
You can look into a 3D printing service company if you want to go that route, most have multiple technologies and can even help model the part in CAD.
We've had good luck with ProtoLabs
www.protolabs.com/
