I went through a few iterations to create a structure for the projector and computer. I started with a basic cubic plinth and right-angled steel to get scale and projector-throw correct. This allowed me projector throw right with my model of projector.
I used the Projector Central Projection Calculator for the model of projector to give me the throw distance and image size.
Conceptually I originally had a bunch of wild ideas to make some craggily peaks and strange formations, but projection-alignment was the priority at this point.