As you can see, I'm jumping all over the place. I've been talking to people on the ablegamers.com forum and it seems there is quite a need for game specific hardware for people with disabilities. Here are a simple d-pad and 4 button combo I tossed together today. These would have velcro on the back and could be placed wherever it would be convenient.
This version uses 6mm momentary siwtches which require a little over 100 grams to depress. I need to design another version with levers inside to reduce this down to below 30grams required as this is a common problem.
Here's a version of a low effort switch
(less than 30 grams required to depress) . The cost,$77, is shocking to me. I've actually already designed and printed my own version of this that works well for virtually nothing in comparison.
Here's mine. It obviously needs a stronger hinge.