I made this iPad keyguard for a student who needed to use a very basic yes/no choice app. He has poor motor control so the boxes allow him to choose only one thing at a time and the fin in the center blocks his hand from moving to the next box. This particular version fits inside his iPad case and we velcro it to the sides. The app is called YES/NO by Answers HD. I am NOT affiliated with them in any way, just found it in an app search. Let me know if you know of a good app to choose from a field of 2-4! (disability, assistive technology, adaptive equipment)
I print it with a skirt but no raft and it has worked fine for me.