Careful…it’s a rabbit hole…and why a lot of progress photos of my LR4 have spools of yarn in the background.
Here’s a short video of it:
And a longer one showing me making a full sock:
Here’s the machine:
Me demoing it for my co-workers:
And some of the socks I’ve made:
I didn’t design it - just made it from existing designs.
It started as this machine:
But just after I built it someone took that design and did some improvements to make it easier to build and released them here:
And I’ve upgraded it with a number of remixed parts from this guy:
I originally used a 3D printed base for it - but found it flexed more than I was comfortable with - so I used the 3D printed base to make some 3D printed templates I used with my router to make a wooden base…of course if you have a MPCNC you could just cut them that way 
I made it just out of curiosity…I’d always found knitting machines interesting from a mechanical point of view. Then a few years ago youtube suggested a video from someone who designed a printed machine because he wanted to understand how they worked better. His was more like the addi/sentro hat machines and he didn’t get it working very well. But it piqued my interest and got me doing some googling. Now I only wear homemade socks and will gladly talk peoples ears off about how great they are 
I half joke that it’s because I adopted a border collie from the local pound and he somehow pushed me towards it. Once I made the initial machine I soon found I was buying nice wool yarn every chance I could…which led to me getting a little spinning wheel and learning how to spin my own yarn (which I’m still terrible at and have yet to make any usable yarn) and my family is pretty convinced that now I’m going to wind up with some sheep because of how I tend to take things a little too far 
Back to the original topic - yes and so does JLCPCB which is the service I used. No commitment…just upload the part and select a process to get a price. Honestly even though metal was the most expensive process by far it was still quite a bit cheaper than I expected it to be. Though I think 9600 resin or MFJ Nylon would make quieter smoother gears that would hold up fine for a fraction of the cost of metal.