I took a course on making gadgets a while back. It's not too difficult...you just need to read a lot about how to set up any special actuators you use (like a touch screen panel) and you have to familiarize yourself with the chosen microcontroller. Arduino is a good starting choice. It also depends on at what level of electronics you want to get into...you could easily buy larger macro parts that take care of a good portion of the complexity (get a mini computer, a touch screen, an arduino board that responds to usb signals) or you can assemble most of that by yourself.