Flag of Vanuatu — construction sheet
Own work. Geometry and dimensions are based on measurements of the flag image that appears in the schedule on page 2 of Vanuatu's  State Flag and Armorial Bearings Public Declaration.
A copy of the declaration can be found at paclii.org. That web page displays the text from the public declaration, but it does not directly display the schedule. There is a download button at the top of the page that sometimes works;  when it is working, the download button will allow the download of a file named sfaabpd392.rtf. The file contains the entire declaration complete with a colour copy of the schedule.
The public declaration is dated March 19,1980 which was just a few months prior to Vanuatu gaining its independence. It starts with the following sentence:

The Schedule to this declaration contains the National Flag, the National Emblem and the National Coat of Arms (hereafter called "the National Symbols") of Vanuatu.— First sentence from Vanuatu's State Flag and Armorial Bearings Public Declaration — 1980

The public declaration does not use words to describe or define the geometry of the flag; the flag is therefore defined only by the image in the schedule on page 2.  The image is a simple bitmap image with no labelled dimensions.

The flag image in the schedule is 471 pixels × 315 pixels which corresponds to an exact ratio of 2:3.
There is no evidence to indicate that the public declaration has been either repealed or superseded.The implication is that the official flag of Vanuatu has a legal aspect ratio of 2:3.
Most of the books and websites devoted to sovereign state flags claim that Vanuatu's flag ratio is one of 19:36, 11:18, or 3:5. None of these books and websites attempt to back up their claims with any official government statute, declaration, or proclamation.

This construction sheet uses a ratio of 2:3 to match the flag image in the schedule on page 2 of the public declaration.
The tusk on this construction sheet is traced from the detail image that appears below the flag image in the schedule.
The ferns shown in the schedule are of too blurry to properly reproduced. Therefore, the ferns on this construction sheet are copied from an old version of Wikimedia's File:Flag_of_Vanuatu.svg; they have been modified to make one fern appear to be in front of the other.
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