The author remixed this model.
I made all of the walls 0.8mm thick and the bottoms 0.6mm, so it's optimized for a standard 0.4mm nozzle at 0.2mm layer height. Depending on how you normally use your printer settings this will save at least half or more on filament as well as print time. As the original shows you will need to print three of the animal trays and just one each of the other two. The third one is just there to hold the deluxe/kickstarter extras.