The “spoils of the Egyptians” is the classic example of God commanding His people to take stuff from pagans and turn it to their own use.
The spoils of the Egyptians show up in Exodus 11:1-2: “And the Lord said to Moses, ‘Yet one plague more will I bring upon Pharaoh and Egypt, and after that he shall let you go and thrust you out. Therefore thou shalt tell all the people that every man ask of his friend, and every woman of her neighbour, vessels of silver, and of gold.’” And then in Ex. 12:35-36: “And the children of Israel did as Moses had commanded: and they asked of the Egyptians vessels of silver and gold, and very much raiment. And the Lord gave favour to the people in the sight of the Egyptians, so that they lent unto them: and they stripped the Egyptians.”
Now, the Golden Calf was made out of the golden “earrings” of the wives and daughters of the faithless Israelites, but the fittings of the Ark and the Tabernacle were made out of gifts of gold and other precious things that the Israelites possessed. Exodus 35:20-29 says: “And all the multitude of the children of Israel going out from the presence of Moses, offered firstfruits to the Lord with a most ready and devout mind, to make the work of the tabernacle of the testimony. Whatsoever was necessary to the service, and to the holy vestments, both men and women gave bracelets and earrings, rings and tablets: every vessel of gold was set aside to be offered to the Lord. If any man had violet, and purple, and scarlet twice dyed, fine linen and goats’ hair, rams’ skins dyed red, and violet coloured skins, metal of silver and brass, they offered it to the Lord, and setim wood for divers uses. The skillful women also gave such things as they had spun, violet, purple, and scarlet, and fine linen, and goats’ hair, giving all of their own accord. But the princes offered onyx stone, and precious stones… and spices and oil for the lights, and for the preparing of ointment, and to make the incense of most sweet savour. All both men and women with devout mind offered gifts, that the works might be done which the Lord had commanded by the hand of Moses. All the children of Israel dedicated voluntary offerings to the Lord.”
And if they were slaves, where’d they get all that gold and all those other rich things? Mostly, they got them from the Egyptians.
The Tabernacle and the Ark of the Covenant were built by two inspired craftsmen working to God’s specs as relayed by Moses. But they were built out of the spoils of the Egyptians.