This is a case I made for my little point and shoot camera. In the lid there is a small piece of glue stick I have glued to the top of the lid that corresponds to the button you push to take a picture. When you put the lid on the box, the sponges you can see around the top edge (blue box) hold the lid up so the glue stick is sitting just above the button. When you push down on the lid, the stick hits the button and takes a picture, basically turning the camera into a single switch. The oversize base allows it to be clamped in place, either on a wheelchair tray or a table.
You can see it in use in the youtube video here: http://www.youtube.com/watch?v=QXsBhQcKAJw