This is the current work-in-progress Regretta Machine, as demo-ed at Maker Faire Ottawa 2018.

If you want to print the manual version, when you raise an lower the needles yourself, you will need to print one each of:

"Outer" "Inner Top" (with or without holes -- the holes are used to mount the inner top to a table if you're driving the machine mechanically). "Inner Bottom"

And twelve of "Triangle".

If you want to try the mechanical version, you can also print one of "Bump" and ... figure out something to drive it because that part isn't designed yet.

Any models related to "Carriage" are old designs, and are just included for completeness.

You'll need some machine knitting needles. A box of 50 is about C$12 on AliExpress -- though they will probably take a while to arrive, depending on where you live.