This is a pictograph of a kiln. The symbol shares a common root with the Chinese character jīn 金. In modern Chinese, jīn means gold or metals. However, Indus sign 4002 follows
the original pictographic usage. It is the noun kiln.
Sample Text Reference:
Mohenjo-daro: Seal: M-798 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 68: Collections in Pakistan: Suomalainen Tiedeakatemia.
Indus Script Sign Number 4002: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.