Green’s Dictionary of Slang

the cut or style of one’s clothes.

1853		‘Cuthbert Bede’ Adventures of Mr Verdant Green (1982) I Ch. x: If he foreswore the primitive garments that his country-tailor had condemned him to wear, and adapted the build of his dress to the peculiar requirements of university fashion.
1860		Hotten Dict. of Modern Sl. etc. (2nd edn) 106: build applied in fashionable slang to the make or style of dress, &c. ‘It’s a tidy BUILD, who made it?’.
1873		Sl. Dict.
1890–1904		Farmer & Henley Sl. and Its Analogues.