What can be achieved with a custom chin implant?

Chin augmentation helps contour and harmonize the jawline
with the rest of the face. Therefore, it is important to
discuss your goals and be examined by a board certified surgeon who can
better assist you with the size of implant and the type necessary as it
related with
the rest of your facial structure. The different implants are not
chosen simply by shape desired. They must be matched with the soft
tissue of your chin and underlying bone structure to obtain the
projection where it is necessary. This is more important when
discussing the type. Also, sliding genioplasty does allow for forward projection, but you will lose width.  In addition, the procedure has more discomfort associated with it due to bone cuts and screws. Many surgeons carve prefabricated implants during surgery to manipulate the implant to the desired result if you choose to move forward with a prefabricated implant.
You also have an option of a customized chin implant that is designed
over a CT scan and fits exactly to the underlying bone and you can
design the projection exactly your liking and also augment the entire jawline if you wish for the desired shape, projection and width. 

It is unlikely that you may need a custom made implant considering number of  implant shapes and sizes available on the market.. As of recently we have chin implants that will increase all three dimensions of the chin (including vertical height). Custom made implants are usually 3-4 times more expensive then standard implants.You should continue your discussion with surgeon(s) who suggested implant augmentation since you seem to have abandon  the idea of SG. Good luck.

Based on your description, it seems as though you know exactly what you are looking for. The chin implant is made of synthetic material that feels just like the natural tissues found in the face. The implants are made in a wide range of sizes and shapes, which allows for optimal customization for each individual face. A custom chin implant may be an excellent option to improve the width and profile of your chin. However, due to the increasing variety, shapes, and sizes of chin implants available, you may not need a custom chin implant.A thorough consultation with an experienced facial plastic surgeon would be an excellent place to start. The experienced facial plastic surgeon would be able to determine what implant types are available or if a custom implant would be necessary. Look for a surgeon who can offer 3D imaging technology to see what your results might look like.

 Chin implants are manufactured in a large array of sizes and shapes, are composed of Silastic, and can be custom carved according to the patient's unique anatomy. Chin implants can give added projection, width, and a slight amount of vertical height, depending upon which implant is used. Chin implants are usually placed through a submental incision under local anesthesia as an outpatient procedure. For many examples, diagrams and more information, please see the link and the video below

You are correct in that a sliding genioplasty will not increase chin width and will actually make it look a little less wide. A custom chin implant can be designed to create all your desired changes and is a true 3D type facial implant.

Hi, I have performed many chin augmentations, using a chin
implant, over the past 30 years.  Chin augmentation, using a chin
implant, will add projection to the chin creating harmony and balance to the
lower face.  I have found placing a silastic chin implant through a small,
curved, incisions under the chin to be very safe, quick, highly effective and
far less invasive than a sliding genioplasty that requires bone cuts with
placement of screws and metal plates.Photos of your face from the front and side would help in the evaluation.  IMHO, and with a long and in depth level of experience using facial implants (both chin and cheeks), it's unlikley that you would need a custom chin implant designed.  There are many styles and sizes from which to choose.  For further consideration.  Following the beauty principles outlined in my book on face and
body beauty, male faces look ruggedly handsome when there is angularity in the
cheeks, chin and mandibular angles.  In addition to chin augmentation,
cheek augmentation with either a dermal filler or cheek implants (for a
permanent enhancement) will add angularity to the cheeks.  Mandibular
angle augmentation with a dermal filler (jaw implants IMHO have too many
unwanted side effects) will add volume, angularity and flare to the jaw line.Hope this helps.