A student at my school spent some time last year updating the calculator code and also making a wonderful box for it. Pictures of the box are below.
The code is posted on github: https://github.com/gcronin/calculator/blob/master/mod/mod.ino .
Haven't had a chance to take much of a look at it, but very impressed by the young man who worked on the box and the code. He has a bright future!!!!