A custom implantable medical device (IMD) may be formed based on an image of a structure of a patient, such as the head of the patient. The custom implantable medical device may include a custom member that at least partially encapsulates a module of the IMD, or may include a custom housing that encloses a module of the IMD. The custom member or custom housing may be constructed to conform to a shape determined based on the image. The image of the head of the patient may include an image of a skull of the patient, an image of a scalp of the patient, or an image of vascular or neurological structures in the head of the patient.