In this chapter, Solomon constructs all of the furnishings of the temple.
This is the second and last "construction" chapter in the Chronicles temple narrative. In chapter 3, Solomon constructed the temple building itself, with its attendant sculptures and the two pillars. In this chapter he finishes the job by constructing several altars, "the sea", various other basins and lampstands, all of which are conveniently detailed in verses 12-16 and 19-22.
The material in this chapter is largely copied out of 1 Kings 7 and they serve analogous purposes in the text. As with much of the temple narrative, it also has a close parallel in the construction of the tabernacle that is detailed in Exodus.
The biggest difference between 1 Kings 7 and this chapter is that Chronicles entirely leaves out the construction of Solomon's palace, which takes up the first 12 verses of 1 Kings 7. This chapter also has a bit less detail on some of the temple furnishings. For instance, 1 Kings 7:28-36 has extensive details on the bronze stands that held the ten bronze basins. This chapter here in Chronicles does not describe the basin stands at all. There are a handful of additional details in Chronicles as well (for instance, v. 9 talks about the "priestly court" and the "large court"), but I don't think any of these differences are substantive.
I think my commentary on 1 Kings 7 covers most of the interesting aspects of this chapter, but there are two additional points I would like to bring up.
First, my readers should note that basically every furnishing has a precursor in the tabernacle of Moses. However, Solomon made most of these furnishings larger and sometimes more numerous. For instance, Moses constructed a bronze basin for washing and Solomon constructed "the sea" for washing. Moses made one table for consecrated bread and one lampstand in the holy place, and Solomon made ten of each. Moses constructed a bronze altar for sacrifices that was five cubits long and wide (Exodus 38:1), Solomon made an equivalent altar that was four times the size in each dimension (verse 1). In most ways Solomon is following the pattern of the tabernacle of Moses, but he is doing it on an epic scale. This leads me to my first point: we can follow the status and health of the temple as a proxy for the status and health of the Israelite nation.
So much of 1 Chronicles and the earlier chapters in 2 Chronicles was the build-up towards this moment, when the temple was constructed. The gathering of gold, bronze, stone and wood and so many other things are all indicators of Israel's royal power and economic strength at this point in their history. Without belaboring the point, the temple is a kind of prestige project that represents the surplus of Israel's wealth and influence, and the amount of excess wealth that they can pump into the temple will ebb and flow over time. Furthermore, invading nations will regularly pillage the temple during Israel's decline, once again depriving the temple of the gaudy status symbols that Solomon is presently stuffing it with. Finally, as Israel sinks into idolatry, the temple will be progressively neglected and damaged, meaning that the temple stands not just for Israel's economic and political strength, but also providing an indication of their nation's spiritual health.
Based on this principle, we can see that Solomon was indeed reigning during Israel's strongest period, and my readers should observe the periodic decline and revival of Israel's temple under future kings as symbolic of their nation's prosperity and devotion to the LORD.
The second point I would like to bring up is the distinction between inner and outer furnishings present in this chapter. Everything built outside the temple is made of bronze and everything build for inside the temple is made of gold. There may be several reasons for this but I think the main purpose is to create a sense of progression. That is, when you are in the outer courtyard, everything is made of bronze, but when you go into the holy place suddenly everything is made out of gold or covered with gold. To those who are going in, it is supposed to show you that as the materials around you change from bronze to gold that you are drawing near to the most holy place where the manifest presence of God dwells. It is a visual symbolism that is meant to portray the spiritual significance of moving from one place in the temple complex to another, with everything centered around the ark of the covenant in the most holy place.
In the next chapter, Solomon finalizes the temple by bringing the ark itself into the new temple.