Exodus 25

2 The Israelites were to give a tithe (described in more detail elsewhere), but from time to time it was necessary to give a special offering for God's work. Tithes and offerings give people another way to participate with God in His work.
3 These offerings were to be used to build a portable sanctuary or tabernacle for God. It was to be made from the finest materials. The symbolism is that God deserves our best. Since the Israelites had just come out of slavery, these treasures would have been what were given to them by the Egyptians. The materials from the self-serving and oppressive Egyptians would now be freely used in service to God. But while this and many sanctuaries since are impressive in architecture and decor, God's most desired sanctuary is in our hearts.
4 Blue and purple materials were both rare and expensive.
5 We don't know exactly what kind of leather was used since the meaning of the word has been lost. Some translations include dolphin and badger, but neither of these seems likely since neither is a "clean" animal as is described later.

Acacia is a common desert tree in Arabia. My understanding is that the wood is that its wood is not strong enough for structures, but it could be used to make furniture. The wood is supposed to be beautiful, but we find in these passages that most or all of the acacia items are covered with gold.

6 God wanted His sanctuary to be pleasing to the eye and the nose (actually all the senses are catered to as is described in other parts). Worshiping God should be a pleasing experience and can be aided by a comfortable environment. Symbolically, when God is in our hearts He wants to find a place of purity and things pleasing to Him.
7 The people were to provide for the priests' clothing as well. The ornateness serves several purposes. The special cloths point out the special work that full time priests participate in. It also might represent the richness of God.
8 This is the symbolic dwelling of God among the Israelites. Of course, God surrounds all things, but the Tabernacle was where God would appear as a theophany. But God desires more than just to surround us, He desires to live within our hearts.
9 The Israelites were not to make a tabernacle of their own design. God would design it and give the verbal blueprint to Moses. Moses would then be the overseer that would make sure that the work was done properly.

If the Israelites would have designed the tabernacle, they may have used an Egyptian design. Not that there is anything wrong with Egyptian styling, but it would reflect their pagan background. God wanted them to make a clean and permanent break from paganism. Another reason God designs the tabernacle is to properly symbolize the process of salvation and heaven (Heb 8-10:22).

10 A cubit is the distance between the elbow and the tip of the longest finger (approximately 18 inches). It is not said if there is a "standard" cubit (e.g., they might have measured Moses' forearm with a string and used it for all their measurements).
11 Most of the most sacred objects are made or overlaid with gold. This represents the richness, royalty, and purity of God.
15 It is interesting that even though the poles were removable, they were not to be removed from the ark. If there is symbolism to this, I would suggest that it relate to God and man. While man could choose to separate from God, he was not designed to do so. While God (represented by the ark) is not diminished in value, men (the poles) serve no purpose apart from God.
16 The contents of the ark were to be the tablets that God wrote for Moses. These tablets had the Ten Commandments and probably some of the other laws written upon them.
17 On judgement day God will sit on the judgment seat, but until then He gives us the mercy seat. At any time in our lives we can go to God to plead for mercy. Those who never seek mercy in this life will only find judgement when this life is over. It is both interesting and important to note that the central symbol in the Israelite sanctuary represents the mercy of God. In Christianity the cross is the combined symbol of blood sacrifice for sin and God's mercy towards us in that Jesus died for the believer's sins.
19 The placement of the cherubim probably represents their placement in heaven. Cherubim are mentioned in a few other places, mostly in the immediate vicinity of God (Gen 3:24, 2 Sam 22:11 and Psa 18:10 - poetic references, Ezek 1, 10, Isa 6:2-4 - called seraphs, and Rev 4:6-8). The cherubim on the mercy seat may have been constructed with only two wings for simplification, as apparently where the cherubim statues made for the temple (1 Ki 6:24).
20 Perhaps the mercy seat was covered to hide a volume above the seat where the glory of God could manifest without being a danger to human eyes. The cherubim are bowed in reverence before God as all creatures should be.
21 Perhaps symbolically mercy triumphs over the Law. It is expressed several times that humans simply can not obey the Law perfectly because of our sinful nature. Anyone who breaks even one of the laws in the smallest manner is worthy of eternal punishment. But God demonstrates time and again that His mercy is greater than our mistakes. In His ultimate act of mercy towards us He sent His Son, Jesus, to live the perfect life that we could not and then suffer all the punishment we deserved. Jesus paid the lawful penalty for us so that God's mercy can combine with perfect justice and still spare our lives. We can now freely approach the mercy seat, confess our sins, ask God to forgive us, and then rely on His strength to help us avoid further sins.
22 We know that God can speak to us anywhere, but the mercy seat was to be a special place for Israel. God would manifest His glory there and speak to Moses directly.
24 This table appears to have had more elaborate decoration than the ark.
25 The "frame" probably provided stability to the table.
28 Unlike the poles belonging to the ark, the poles from the table were probably removed while the table was in service. Perhaps an additional reason the poles were not to be removed from the ark was to avoid confusing them with other poles.
29 The table's accessories were to have the characteristics of purity and royalty.
30 The title for the bread is commonly translated as "showbread" or "bread of the Presence." The name for this bread comes from a common word that roughly means "in front of." The word also connotes "favor" or "honor." The bread is described in Lev 24:5-9.
31 The lamp stand provided the only light inside the tabernacle.
32 There where seven lamps in all: three on each side and one in the middle.
33 The lamp stand was to resemble an almond tree blooming in the spring.
34 A flower decoration was to be placed under the central lamp and one placed under where each branch joins the center branch.
39 I have seen "talent" defined as 72 or 94 pounds.
40 Again God reminds Moses to follow the plan that God showed him.