It is generally not recommended to put plastic toys directly on a cake that will be consumed. While plastic toys can add visual appeal and thematic elements to a cake, they are not safe for consumption and can pose a choking hazard. If you wish to incorporate plastic toys into the cake decoration, it is best to place them on top of a piece of wax paper or parchment paper before positioning them on the cake. This will help ensure that the toys do not come into direct contact with the edible portion of the cake.