In this case you would just make a custom foot orthotic and add either a morton's extension or full extension plate (depending on site of amputation) to increase the biomechanical leverage. In place of the missing digits, etc. a toe filler would be added.
This is of course depends what the patient is after -- something that will actually work for them, or something merely for aesthetics.
I find this extremely fascinating and have read a few articles about it in my O&P magazines, it has been out for a while, just not approved of by whatever organization in the US yet:
Osseointegration:
Osseointegration is a method of attaching prostheses directly into the bone, I've seen a few pictures of fingers too.
Someone who specializes in prosthetics would be known as a prosthetist. Orthotist in regards to orthotics. Or if specialized in both, a CPO, Certified Prosthetist Orthotist.
Taking on the responsibilty of fabricating prostheses is both time-consuming and expensive. There are several ways that one can become a CP, CO, or CPO --
www.abcop.org,
www.bocusa.org. There are universities that you actually attend (2 years I believe) to become qualified, one being Northwestern. You can also apply to be one after X amount of years of training under a CP or CO.
As a podiatrist, you can definitely handle the fabrication of a prosthesis for missing toes. It becomes trickier when dealing with chopart amputations etc -- that would revolve more around the fabrication of a custom-made AFO with forefoot filler.
Symes, BK amputations, definitely out of your scope without proper training. AND DON'T FORGET EQUIPMENT!
Grinders, bandsaws, ovens, plastics, etc... of course you could always send it out... but what do you do for adjustments? Send the item out everytime? That would become very frustrating for both you and the patient.
Parts also cost a fortune, prosthetic feet (e.g. carbon feet made by companies like Ossur, Ottobock, etc.) can sell for HUNDREDS of dollars, we just purchased one that was $700 -- and that was our discounted rate.
Hope this helped.