What sort of stuff have you designed?
I am interested in interfaces for people with motor and as a result communication problems, which is common in ASD. The most I done so far is design some touch screen software for reading pdf files. The idea was to test a concept of interface other than WIMP, which we have got rather stuck on but can be very inaccessible to many people. The pdf reader was just an application of this.
Interface is the most important thing really. You do need to get the physical interface right first, before anything else like software. We take interfaces like keyboards for granted. I have a few ideas but can't be sure whether this will work until they are tried. Unfortunately the so called accessibility market is basically getting unsuitable "boys toy" like PDAs and sticking some superficial packing on them, in some case attempting to limit the function so it can’t be resold, and then niche marketing them to parents of disabled children.