Why cakeify videos work
The format has been reliable since it started circulating because it exploits a very cheap prediction error. Your brain has a firm model of what is inside a shoe, and the cut violates it in under a second. That is the entire mechanism, which is also why the reveal has to be clean — a mushy or ambiguous interior gives the brain time to hedge, and the surprise dissolves.
Choosing a subject
Go for objects with an unambiguous material read: leather, metal, moulded plastic, painted wood. Soft or food-adjacent subjects blunt the effect because cake is already a plausible interior. A plain, high-contrast background helps the model hold the object's outline steady through the approach, which is the part that most often goes wrong.