What's is the right answer: 3-D-printed component vs 3-D printed component vs 3D printed component vs 3D-printed component? [duplicate]

How do you correctly abbreviate that something is in "three dimensions" in formal writing? As per the title, would you write either "3D", "3d", or "3-d"?

I want to write something like:

The figure contains a 2D widget (left) and a 3D gadget (right).

Additionally, if I use the full phrase in a sentence, I gather that I write

The three-dimensional gadget is composed of independent two-dimensional widgets.

i.e. using a hyphen and the word "three". Would it also be allowed to write "3-dimensional"? Especially in a context where I want to contrast it with something else "2-dimensional" in the same (or adjacent) sentence, as the numerals stick out more?

I am searching for an answer to the same question. I wouldn't use 3d, 3-d, or 3-dimensional because I have never seen them. Longman dictionary says three-D or 3-D (Longman), but Oxford also says 3D (Oxford). So I think 3D or 3-D are accepted.

According to this Ngram, both 3d and 3D are acceptable to use. Furthermore, different dictionaries show a different form of abbreviation for "three-dimensional". Some are 3-D, some 3D, some 3d, and so on.

From this I would conclude that none of these are incorrect to use. 3-dimensional is not something that is recommended though, as shown from the results.

Ngram also shows that "three-dimensional" is used just as much as 3D or 3d. Perhaps that is the best option to consider using in formal writing, since formality doesn't have fondness for abbreviations.