Tabernacle Artisans, the Sabbath and the Tablets of the Testimony
Bezalel of the tribe of Judah and Aholiab of the tribe of Dan were chosen to build the items for the tabernacle. Though naturally born with these talents—and, as a result, skilled in working with gold, silver, bronze, stone and wood, as well as in carving and embroidered work—the most important thing to notice is that, just as He did with the garment makers, God also filled them with wisdom by His Spirit to enable them to accomplish this most important responsibility.
Also in this chapter, God stresses that it is important to keep His Sabbaths (weekly and annual), as they are a sign between God and His people. It serves as a visible badge and witness to others manifesting those who serve the true God. Furthermore, verse 12 says, "It is a sign...that you may know that I am the Lord who sanctifies you." Thus, it is a sign that regularly points us to the true God. Indeed, the weekly Sabbath memorializes creation, as stated in this passage—and creation points to the Creator, the true God. The Sabbath is a reminder that we do not worship "gods" of rocks and trees, sun moon or sky, or figments of human imagination, but the very Creator who made all these things—including the human mind. And all of God's Sabbaths reveal His plan for the salvation of all mankind. Notice that the Sabbath is given as a special covenant—a perpetual covenant—distinct from the Sinai covenant (verse 16).
Indeed, God's Sabbaths are important for us even today, as He said they would be "a sign between Me and the children of Israel forever" (verse 17). Notice: "...for in six days the Lord made the heavens and the earth..." (same verse). Why would this only be for the Jews alone? That wouldn't make any sense. Rather, it is clear that, as Christ said, "the Sabbath was made for man" (Mark 2:27-28)—that is, for all mankind. What ties it all together is that all people must become part of spiritual Israel (compare Romans 11:17, 24; Galatians 3:28-29; Genesis 6:16)—and that is defined as those who obey God's law (Romans 2:25-29), which includes His Sabbath.
After God finished talking with Moses, He gave him the two stone tablets of His Ten Commandments, which He had already written (Exodus 24:12) with His very finger (Exodus 31:18). Though we often think of each of these tablets as containing separate sections of the Ten Commandments, it is possible that "all ten commandments appeared on each tablet. Middle Eastern treaties were typically written in duplicate" (Nelson Study Bible, note on 24:12). As these were "tablets of testimony," it would seem that this would provide the testimony of "two witnesses," a requirement of God's law for judgment to be carried out (Numbers 35:30; Deuteronomy 17:6; Deuteronomy 19:15). Perhaps that is even one reason the Ten Commandments are recorded twice in the Bible (Exodus 20; Deuteronomy 5). Still, as the front and back of the tablets were written on (Exodus 32:15), it is possible that the first four commandments, concerning duty to God, were inscribed on one side, while the last six commandments, concerning duty to man, were engraved on the other side. In that case, putting the two tablets together, with one turned over, would still yield the traditional picture.