Verse 11 already taught that he made the Siros and Ya'im!
'Rashi': (a) Our verse teaches that they were of copper; this was not taught above. (b) Our verse adds the Mizlagos.
Who made all these Kelim?
Radak: Churam made them k'Aviv, i.e. like his father [used to make], who was a famous craftsman. His father knew to work with gold, silver, copper? (2:13). The prefix 'Kaf' is omitted, just like "Lev Some'ach Yeitiv Gehah" (Mishlei 17:22) is like k'Gehah.
Ralbag: Churam and his father made them. It is as if it says v'Aviv; the prefix Vov is omitted. Also his father was skilled with copper ? "v'Aviv Ish Tzori Choresh Nechoshes" (Melachim I, 7:14).
Malbim (14-16): The father made them; the son was not so skilled with copper Memurat. We infer that his son made the Mechonos (verse 14).
What is "Maruk"?
'Rashi': This is [cleaned,] like "Mirku ha'Remachim" (Yirmeyah 46:4), "u'Morak v'Shutaf ba'Mayim" (Vayikra 6:21). In Melachim I, 7:48 it says "Memurat." This is like "Ki Yimaret 1 Rosho" (Vayikra 13:40); the Targum is 'good copper.'
I.e. the head is emptied of hairs. Here, the copper is empty of impurities. (PF)
