《天工开物·中篇·冶铸》
大体而言，铸造铁钟的模子不需要耗费太多的油蜡，方法是：先用黏土制成剖成左右两半的或是上、下两截的外模，并在剖面边上制成有接合的子母口，然后将文字和图案反刻在外模的内壁上。
凡铁钟模不重费油蜡者，先埏土作外模，剖破两边形或为两截，以子口串合，翻刻书文于其上。
Generally speaking, it does not cost too much oil and wax to cast an iron bell. The method is: first use clay to make the outer mold cut into two halves or two sections, and make a dovetail joint on the cut surface, and then carve the characters and patterns on the inner wall of the outer mold.