I had added a cube and deleted the vertices in order to select the ones needed to have my faces created. After having my first wedge, duplicated it without linking and inverted it on top of the other. I decided to join both of them and enter edit mode in order to create the remaining faces.
After the periscope was ready, still in edit mode, I selected the bottom edge, moved the cursor to that selection, exited edit mode, and in object mode selected tools and then set origin to 3D cursor. Moved my cursor to the center via snapping, and then moved the periscope as selected object to the 3D cursor.
That was that!.