Techniques for forming a header for an implantable medical device via a two-shot molding process are described. The two-shot molding processes may include a first molding step that creates a first-shot assembly and a second molding step that creates a second-shot assembly. The first-shot assembly may be formed to include one or more protrusions configured to interact with a second-shot mold and/or molding material in the second molding step. The second molding step may be configured to overmold the first-shot assembly. The header may include an attachment plate at least partially embedded in molding material and configured to be mechanically coupled to a body of the implantable medical device.