This very fine cast brass mould dates to at least the 18th century and probably earlier. Such moulds were used in Tibet to make votive plaques.
Clay mixed with ritual materials such as ground incense, grains and/or the ashes of a sacred individual would have been pressed into the mould, removed and then dried in the sun. (Prosser, 2010, p. 87).
Called a tsha-tsha in Tibet, such a plaque increased the Buddhist merit attributable to the individual who commissioned it, and even to those who viewed it. Tsha-tshas often were left as offerings at sites of pilgrimage.
The example here has been cast with an image of Vajrasattva, surrounded by an exceptionally fine line of lantsa script.
The mould has an attractive colour and a central finial or pull on the reverse.
It is in excellent condition. It is sculptural in its own right. The mould has a splendid patina, deep colour and softness from handling and age.
References
Proser, A., (ed.), Pilgrimage and Buddhist Art, Asia Society Museum/Yale University Press, 2010.