Why does it say "Shenayim"?
Malbim: This teaches that they are different. One was a male form, an influencer, and the other a female, a recipient. It says in Melachim I, 6:23 "Shnei Cheruvim", which shows that they are the same. I.e. their measures were the same. Also in the Torah, the command was to make "Shenayim Keruvim", but it says that they made "Shnei Cheruvim" (Shemos 25:28, 37:7) for this reason (they were the same size, but different genders).
What is "Ma'ase Tza'atzu'im"?
'Rashi': This is like "ha'Tze'etza'im veha'Tzefi'os" (Yeshayah 22:24); the Targum is Venaya, the forms of boys and girls. He made the Keruvim like a youth. It was of wood, and then he covered it with gold. In Melachim I, 6:13 it says that he made the Devir "Shnei Cheruvim Atzei Shamen." Here it does not mention anything of wood [in the Kodesh ha'Kodoshim], for its honor.
Radak: Some say that it is made like engraving.
Malbim: It looked like they were flying. Their wings resembled birds' wings, which can spread or contract. The root is Tza'ah, which refers to inner motion ? "Miher Tzo'ah Lehipase'ach" (Yeshayah 51:14). This is close to Zo'eh and So'eh. The two root letters are doubled, like Sha'ashu'im, Ta'atu'im.
