Flag of Thailand — construction sheet
Own work. Geometry and dimensions from Thailand Flag Act

the National Flag which is rectangular in shape with 6 part width and 9 part length, divided into five stripes throughout the length of the flag; with the middle stripe being 2 part wide, of deep blue colour, and the white stripes being 1 part wide next to each side of the deep blue stripes, and the red stripes being 1 part wide next to each side of the white stripes.
The National Flag shall also be called “the Tri-Rong flag”—  chapter 1, section 5, sub-section 1 of the Thailand Flag Act
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