Can a custom jaw implant make my face symmetrical?

Without an exam your question cannot be answered.  You will need to see an Oral/Maxillofacial surgeon to see if othognathic surgery, genioplasty or using an implant is best for your specific case. It should be noted that patients with severely weak jaws or abnormally functioning jaws may be better treated with other facial surgery (orthognathic surgery), although a chin augmentation may be an option at a later time. These patients should seek the advice of a plastic surgeon to determine which course is right for them. Here is some information to help you make this decision: Candidates for Chin Augmentation - Patients whose chin profiles are weak but have normally functioning jaws are candidates for Chin Augmentation. Many of these candidates have used injectable fillers in the past to strengthen the protrusion of their chins, but are looking for a permanent solution. If you are one of these patients, then you are a likely candidate for chin augmentation

In general, balance may be achieved by using a silicone angle of jaw implant. The surgery is safe, and accomplished with local anesthesia and IV sedation in the office. The implants are permanent, however, if you were dissatisfied with the results, the implant can easily be removed and you would look the same as before the surgery. Find a surgeon who places facial implants for a consultation.

Without looking at pictures of your face, the answer to the best solution can not be determined. But assuming that it is a bony deficiency from one side to the other a jawline implant may be of benefit. The question is whether it would need to be custom made or not.