So the faceplate referenced is just a snap on cover of the metal hinge? I sure hope so because I don't have a good feeling about using a 3D plastic on an otherwise vital safety device (safety as in keeping your handle bars secure, who here has seen the results of a handlebar breaking away from a stem while riding?)

My concerns with these types of questions is less for the OPs (sorry to sound like I don't care) but more for others who read this type of stuff and have less abilities to assess the situation and forge ahead (sort of pun intended), making their load supporting part out of a material with far less strength.

As long as the thread makes clear what the 3D part is for and what it isn't I'm OK with cosmetic bits being plastic; 3Ded, machined, cast/molded independent. Andy