Exodus 25:9 According to all that I shew thee, after the pattern of the tabernacle, and the pattern of all the instruments thereof, even so shall ye make it. The sanctuary, and all that was in it, was made according to the pattern given to Moses by God on the mount.
Exodus 25:10 And they shall make an ark of shittim wood: two cubits and a half shall be the length thereof, and a cubit and a half the breadth thereof, and a cubit and a half the height thereof.
The ark was made of shittim, or acacia wood, which was a very long lasting wood. This was covered by gold. (see comments on gold in the section on "Symbolism")
Exodus 25:11 And thou shalt overlay it with pure gold, within and without shalt thou overlay it, and shalt make upon it a crown of gold round about.
1 Kings 8:6 And the priests brought in the ark of the covenant of the LORD unto his place, into the oracle of the house, to the most holy place, even under the wings of the cherubim's.
2 Chronicles 5:7 And the priests brought in the ark of the covenant of the LORD unto his place, to the oracle of the house, into the most holy place, even under the wings of the cherubim's:
In the inner apartment was the ark, which was the most sacred object connected with that system of worship. It was a chest of precious wood, overlaid within and without with pure gold, and having a crown of gold about the top. In the ark were placed the tables of stone upon which God had engraved with his own finger the ten commandments. It was made expressly for this purpose, and hence was called the ark of the covenant, and the ark of the testament, since the ten commandments were God's covenant, and the basis of the covenant made between God and Israel.
The pure gold which covered the ark, "within and without", symbolized the righteousness of Jesus which replaces our sinful selves when God views us, He sees only the righteousness of Jesus when we accept Him as our Saviour.
Pure Gold = Christ's righteousness and purity (which may be ours when we come to Him and forsake all for Him.) Without this we cannot be saved.
Malachi 3:3 And he shall sit as a refiner and purifier of silver: and he shall purify the sons of Levi, and purge them as gold and silver, that they may offer unto the LORD an offering in righteousness.
Shittim or acacia wood = our righteousness, which is as filthy rags,
Isaiah 64:6 But we are all as an unclean thing, and all our righteousness are as filthy rags; and we all do fade as a leaf; and our iniquities, like the wind, have taken us away.