Just a thought. Could you use one of the protective covers they have for keeping keyboards clean?
The cake description says she made her own mold...
I did a quick search for ready-made molds, and only found small ones:
I like Mike's idea too.
Sorry I couldn't be of more help!
I made a computer using the long loaf pan for the base of the keyboard and then classic candy molds for the keys. There is a picture in my photos if you want to see what it looks like. It was for a grooms' cake. It was in the Wilton book a couple of years ago.