The images below are only a selection of depictions illustrating the uses of the tetrahedron in Tantric Buddhist art. For more information see the short article Sacred Geometry: Part 2.
The painting of Vajrayogini Tinuma depicts a secondary figure of one of the Twenty-one Taras of the Suryagupta tradition holding a fire pot in the shape of a tetrahedron as does the god Agni (a secondary figure in the Mandala of medicine Buddha).
Jeff Watt 5-2014 [updated 2-2020, 1-2021]
The Glorious King of Tantras That Resolves All Secrets
1.3. Imagine that, like one candle lighting another, The syllable hūṁ at the heart Projects a black-hued e, Which forms a vast, deep triangle.
1.4. The three corners are enlightened body, speech, and mind. This signifies the destruction of the three poisons. The sides are the three liberations. This signifies the destruction of the ten non-virtues That emerge from ordinary body, speech, and mind.
1.5. The dharma body is immaculate, And therefore [F.187.b] naturally all-pervading. This is the significance of vast.
1.6. Since even the noble listeners, solitary realizers, And bodhisattvas as well, Do not realize the dharma body, It is explained with intention as deep.
(Toh 384. The Glorious King of Tantras That Resolves All Secrets. དཔལ་གསང་བ་ཐམས་ཅད་གཅོད་པའི་རྒྱུད་ཀྱི་རྒྱལ་པོ། · dpal gsang ba thams cad gcod pa’i rgyud kyi rgyal po Śrīguhyasarvacchindatantrarāja). 84000: Translating the Words of the Buddha.(The images below are only a selection of examples from the links above).