I was just a kid when "Raiders of the Lost Ark" made its debut in 1981. I remember my first thought upon hearing of this new motion picture was that it would be all about the discovery of Noah's Ark. Oops. Wrong ark.
When God meets with Moses up on the mountain, He begins revealing to him all the things that God would like constructed in order for His Presence to go with the Israelites. The tabernacle and its furnishings are to be a sanctuary (or holy place) patterned after heavenly realities. [Read Hebrews 9 to hear more about this!] After describing the donations that will be needed from the people (vs. 2-8), God begins by commissioning the building of an ark.
Now this ark is not a gigantic floating vessel with room for specimens of every kind of animal. The word "ark" generically means a carrier, a container to hold and protect something valuable. Thus Noah's Ark and Moses' Ark (the Ark of the Covenant) share something in common: they are both meant to house and protect something very precious.
In the case of the Ark of the Covenant, the ark is a box made from acacia wood and overlaid with gold and carried by poles. It is used to contain the tablets of stone upon which the commandments are written. As time goes on, the ark will also be designated to house other things as well (Aaron's rod and a jar of manna). The Ark of the Covenant is the holiest physical article the world has ever seen. It is to be the centerpiece of the Holy of Holies, and God's presence will be said to appear between the wings of the cherubim on the top of the ark.
The ark is the first item mentioned on Moses' list to be constructed, but other altar furnishings are described as well in chapter 25. Also needed will be a table for the bread of the presence and a lampstand. These represent God's presence and are instrumental in His worship.