Tosefta על מנחות 56:12

A menorah is not valid unless it is produced a solid block [of gold (see Menachot 28b:4)]. [If it is fashioned from] filings, it is invalid, and if it is made from other types of metal, it is valid. Trumpets are not valid unless they are fashioned from silver. [If] they are fashioned from [silver] filings, they are valid. [If] from other types of metal, they are invalid, and consequently it is said, "[What is] invalid in a menorah is valid in trumpets, [and what is] invalid in trumpets is valid in a menorah."