You could make it whatever shape you want. Then program it to emit whatever usb key codes you want (there are existing libraries to do this quite easily). This

You could make it whatever shape you want. Then program it to emit whatever usb key codes you want (there are existing libraries to do this quite easily). This one happens to emit standard qwerty key codes, but there are many more that do other things. For example, there are standard key codes to launch a browser or the calculator (and some keyboards have buttons to do that too). You could also make it emulate any kind of standard usb HID (human interfact device). This one is a keyboard, but you could make something that identifies itself as a mouse, game controller, etc.