Metal inside a printed object

Experiment: Print the part "in" (blue) this is the metal part. Print the part 'out' (black)and when it is still open stop the printer temporarily. Place the metal part (blue) inside of the part 'out' and pass on the printing. Now the metal part is inside of the object. Any shape you can make inside of a printed object. (metal nuts, inlayers and fasteners ect.)