I have a lot of hardware lying around and for this particular project I have almost all the things that I need. A 7" touch screen compatible with a Raspberry PI (from http://www.teamfdi.com/) a Raspberry PI B+ and a GSM module. Took a couple of pictures to add to my log.

Here is the setup that I will be mounting on my office door. The screen is touch screen so I haven't decided whether I would be using buttons for an interface or not.