There's only one firmament called "the firmament", not "the firmaments", in direct words that God made as per Genesis 1:6-8.

And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters. And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so. And God called the firmament Heaven. And the evening and the morning were the second day.
Genesis 1:6 - 8 KJB

[19] The heavens declare the glory of God; and the firmament sheweth his handywork
Psalm 19:1 KJB

And the likeness of the firmament upon the heads of the living creature was as the colour of the terrible crystal, stretched forth over their heads above.
Ezekiel 1:22 KJB

𝔅𝔦𝔟𝔩𝔦𝔠𝔞𝔩 𝔽𝔼