Rolling diapers for a diaper cake requires a specific technique to ensure stability and ease of assembly. To begin, lay out a diaper on a flat surface with the front side down (the side that opens), making sure both sides are folded inward towards the center. Next, start rolling each diaper tightly from the front toward the back while applying gentle pressure to keep it secure. Once rolled up, use a rubber band or string to secure it in place temporarily until you've rolled all the diapers you need for your desired size and shape of diaper cake.