One example is of Akaki Kuumeri’s One Handed Dual Sense snap-on 3D printed solution. This is for right-hand use, and if printed in mirrored aspect, left-hand use. Until the likes of Sony and Microsoft create or license an affordable one-handed controller for the modern age, these things are a stop-gap to be grateful for.
Other examples include extended Xbox One button extenders, accessibility switch stands and much more.
Competition head Caleb Kraft has long been advocating for highly affordable solutions at The Controller Project. Do take a look at these as there’s much potential there. The next trick is to find local 3D printing experts with quality machinery to make these for people.