That might be ok for that piece pictured because it is sandwiched between the carbon arm pieces. However, the other piece needs to be much stronger because there is a lot riding on that joint. If that hinge breaks under thrust load the whole arm, motor, and prop assembly will fly forward and cut you and your lines to pieces. I wouldn’t feel comfortable with either part of the hinge 3D printed. Even with carbon reinforced plastic you are still only as strong as the layer bonding.
I want to cut weight too but I’m not looking at ounces or grams but rather pounds! I’ve been flying with 4 Bonka batteries which total 24 lbs. When I fly with only 2 batteries I don’t like how hot the batteries and wires get even with 8 AWG wires on the batteries (just bought a second set of 4 and they have 8 AWG instead of 10 AWG). I love losing that 12 lbs but everything stays much cooler with 4 batteries. Maybe I can get some batteries with a higher c rating and even heavier gage wire because I’d really love to lose that weight!