Some companies have used investment casting with RP models to produce metal tooling. Most of the tools cast so far have been in aluminum,

but there are some examples of tool steel molds. If a steel or hardened alloy cavity is required, either for mechanical strength and thermal cycling or due to high-volume production, investment cast tooling can offer an alternative to open cast tools, such as the kirksite process. By making a sacrificial RP model of the desired cavity, the lost wax process can be used to replicate the part in a metal.

The RP pattern is first invested in multiple layers of ceramic slurry, which are allowed to dry between coats. After the shell has dried, the ceramic shell and invested part are fired. The firing process sinters the ceramic shell and causes the invested model to be burned out. After firing, any ash residue is washed from the ceramic shell. The molten alloy of the tool material is then poured through a gating system into the void left by the RP pattern. After solidification and cooling, the ceramic shell is fractured and the newly formed metal cavity is removed and post-process machined.

Investment cast tools have been used for injection mold cavities and die casting tools. However, due to the unpredictable contraction of the casting process, it is difficult to maintain a high level of accuracy with this tooling process.
An advantage to the process is that you can get better detail than with cast aluminum or kirksite tooling. Distortion, limited accuracy and the need for finish machining are disadvantages.