Why does it say "va'Yatzar"?
Radak: He made their form in the ground into which he poured [the molten copper].
Gra: He poured [molten copper] (Malbim - into a mold).
Were the pillars solid, or hollow?
Radak: They were hollow, like it says in Yirmeyah (52:21) "Navuv"
What are the two pillars?
Rashi: They are the two pillars of the Ulam, called Yachin and Bo'az (verse 21).
Here it says that they were 18 Amos tall. In Divrei ha'Yamim II, 3:15 it says that they were 35 Amos tall!
Rashi: He poured (molten copper and formed) both at once (and later separated them). Radak: He formed them lying down. This is why it says there 'length' and here it discusses the height, after he erected them.
How thick were the pillars?
Rashi (from Eruvin 13b): Their diameter was four, like it says in Yirmeyah (52:21). The circumference is three times the diameter.
What was the circumference of the first pillar?
Rashi, based on Targum Yonasan: The verse taught about the second; we learn from it to the first. They were the same. Radak - likewise, the verse taught the height of the first; we learn from it to the second. It does so for conciseness; this is Midah 19 of the 32 Midos of expounding, of R. Eliezer Bno Shel R. Yosi ha'Gelili. Malbim - Yirmeyah 52:21 gives the height of "ha'Echad" and its circumference; this shows that they were the same.
QUESTIONS ON RASHI
Rashi writes that he formed both at once, and later separated them, and each was 18. If so, initially the length was 36. Why does Divrei ha'Yamim II, 3:15 say that they were 35 Amos?
Rashi: One Amah (the half Amah on top of each) is not counted, for it was made unlike the rest of it, like it says below (verse 22) "v'Al Rosh ha'Amudim Ma'ase Shushan" (it was much thinner - refer to 7:19:1:1) 1 . Malbim - after separating them, he beat the top with a hammer Ma'ase Shushan; this extended each half an Amah.
'Rashi' (Divrei ha'Yamim II, 3:15): It mentions there a Tzefes on each, i.e. a hollow crown that covered five Amos. Its thickness was a half-Amah, this added to the height of each half-pillar.
Radak: A half Amah of each entered the crown. 2
Gra: When he formed them, an Amah of one entered the other.
'Rashi' (Divrei ha'Yamim II, 3:15): This is wrong. Why should it not be counted, even if it is different?!
I.e. Divrei ha'Yamim does not count the part of each pillar that would later be covered by the crown.
