The main goal of the creation of the Mishkan was to rectify the sin of the idolatry to the golden calf.
Increasing Holy Passion
Hashem took the Jews out of Egypt with great wondrous miracles, split the sea for them and gave them the Torah in tremendous noise and thunder, revealing his awesome, fearsome G-dlniess. Yet despite all this, right afterwards the Erev Rav managed to stumble them with the horrible sin of idolatry to the golden calf. When Moshe saw this, he realized the great power the Yetzer Hara has to trap people in this world. He therefore introduced the creation of the Mishkan whose fundamental factor was charity, which increases a person's passion for holiness. This gave the Jews the passion needed to overcome the Yetzer Hara despite any darkness he hurls a person into.
Nullifying Lust for Money
Spiritually, idolatry and the 'lust for money' are very intertwined since a person only lusts for wealth out of a lack of faith in Hashem and belief in Divine providence, which are elements of idolatry. These cause a person to always worry where his money and livelihood will come from or if he already has money, he desires more and more. Therefore the Jews were given the opportunity to donate to the Mishkan since charity given completely for the sake of heaven, to completely righteous causes is a powerful rectification for the lust of money.
The residue of the Mishkan's holiness remains forever, even after its destruction and it continues to protect the Jewish Nation. It is for this reason that the Mishkan was always being taken apart and being rebuilt, to show that its power remained even when it was dissembled.
Gold & Silver
Although in their lower manifestations gold and silver are crude oftenly abused physical items, in their roots they are very lofty elements that are a big part of Hashem's glory and are therefore important materials in the Mishkan. It is only below that they fell tremendously, to the point that most of the world strays from Hashem due to them.
Additionally the gold, silver and valuables alluded to the good points in each Jew. Every Jew, even the lowest one, has a good point that no other Jew has, with which Hashem glories. After the sin of the golden calf, Moshe had to work hard to search out and find the good points in the Jews, whose bad elements had just been very apparent. When the Jews brought their donations, each according to the goodness of his heart, they revealed their goodness that was concealed inside of them. Moshe then took these good points which came out in the donated valuables, which also happen to be the extracted good points of physical reality and built the Mishkan from them, gathering them into a single location, proving once again that the Jews were filled with goodness.
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