A trifold or a PowerPoint
The conflict that keeps Rainsford awake was that he couldn't sleep because he was hearing weird sounds. That was an internal conflict because it was with himself and he couldn't put himself to sleep. But also, he was worried because of all the things that the general Zaroff told him about how he invented a new animal to hunt which was men.
ARE U FILIPINO? KUYA OR ATE
He used the money he made to buy more and more equipment sounds like the best choice to show his passionate about his inventions!