Construction time: the sanctuary and priests robes: Exodus 37–39
For a bunch of recently escaped slaves surviving in a hostile desert, the Tabernacle was an extraordinary achievement.
Even more extraordinary was that the whole idea was God’s: the fine robes, the expensive jewels, the materials:
All this was done just as the Lord had commanded Moses.
So why would God need a lavish tent? He doesn’t really need it, but it gave His people a focus in their camp, kept them busy, almost certainly trumped any golden calf the people had ever seen, and everything had a symbolic value that would have been well understood at the time.