Matthew Henry on Exodus 27:1-8

In the court before the tabernacle, where the people attended, was an altar, to which they must bring their sacrifices, and on which their priests must offer them to God. It was of wood overlaid with brass. A grate of brass was let into the hollow of the altar, about the middle of which the fire was kept, and the sacrifice burnt. It was made of net-work like a sieve, and hung hollow, that the ashes might fall through. This brazen altar was a type of Christ dying to make atonement for our sins. The wood had been consumed by the fire from heaven, if it had not been secured by the brass: nor could the human nature of Christ have borne the wrath of God, if it had not been supported by Divine power.