SB 2.5.33

tadā saṁhatya cānyonyaṁ
 bhagavac-chakti-coditāḥ
sad-asattvam upādāya
 cobhayaṁ sasṛjur hy adaḥ
Synonyms: 
tadā — all those; saṁhatya — being assembled; ca — also; anyonyam — one another; bhagavat — by the Personality of Godhead; śakti — energy; coditāḥ — being applied; sat-asattvam — primarily and secondarily; upādāya — accepting; ca — also; ubhayam — both; sasṛjuḥ — came into existence; hi — certainly; adaḥ — this universe.
Translation: 
Thus when all these became assembled by force of the energy of the Supreme Personality of Godhead, this universe certainly came into being by accepting both the primary and secondary causes of creation.
Purport: 

In this verse it is clearly mentioned that the Supreme Personality of Godhead exerts His different energies in the creation; it is not that He Himself is transformed into material creations. He expands Himself by His different energies, as well as by His plenary portions. In a corner of the spiritual sky of brahmajyoti a spiritual cloud sometimes appears, and the covered portion is called the mahat-tattva. The Lord then, by His plenary portion as Mahā-Viṣṇu, lies down within the water of the mahat-tattva, and the water is called the Causal Ocean (Kāraṇa-jala). While Mahā-Viṣṇu sleeps within the Causal Ocean, innumerable universes are generated along with His breathing. These universes are floating, and they are scattered all over the Causal Ocean. They stay only during the breathing period of Mahā-Viṣṇu. In each and every universal globe, the same Mahā-Viṣṇu enters again as Garbhodakaśāyī Viṣṇu and lies there on the serpentlike Śeṣa incarnation. From His navel sprouts a lotus stem, and on the lotus, Brahmā, the lord of the universe, is born. Brahmā creates all forms of living beings of different shapes in terms of different desires within the universe. He also creates the sun, moon and other demigods.

Therefore the chief engineer of the material creation is the Lord Himself, as confirmed in the Bhagavad-gītā (9.10). It is He only who directs the material nature to produce all sorts of moving and nonmoving creations.

There are two modes of material creation: the creation of the collective universes, as stated above, done by the Mahā-Viṣṇu, and the creation of the single universe. Both are done by the Lord, and thus the universal shape, as we can see, takes place.