As per ancient Shastra, Tantraraj Tantram, Shree Yantra made by Lead, (Lead is part of Brass) and Bronze gives negative results. Almost every Shree Yantra available in the market is made by prohibited metals i.e. either Brass or Bronze.
Shiskaansyaadishu Punah Purvoktvipritkrit Falkaayaam Pate Bhitao Sthaapyenn Kadaachan,
Sthaapitam Yadi Lobhen Mohenaagyaantoapi Waa Kulvittampatyam Cha Nirmulyati Sarvthaa
