Few years ago, I had serious doubts about if 3D printed gears would work for most of my needs. Today, I have solved and used 3D printed gears for various purposes but mostly for my RC designs with success!
These would be the pinions you need if you started with some of my 1/10 RC projects, as they use Mod 1 pitch gears, the same as the suggested to buy central differentials. They all have a pressure angle 20º.
I use to supply the 14T Mod 1 motor pinion with chassis, but probably you want more final speed or more torque... then is time to change that pinion for a bigger or smaller one ;)
You will find pinions from 10T (teeth) to 23T, for both M3 and M4 grub screws, those are 28 models!
The pinions have the number of teeth over the hub part, I hope that helps identifying them when you have a bunch around there.
I have also made some chamfers so you avoid partially the problem of first layer elephant foot, anyway try to do your best for the first layer.
Enjoy your functional prints!