This is the only time that the phrase ויקהל משה,
Moses assembles, appears in the entire Torah. Why is this?
The sin of the Golden Calf divided the Children of Israel, blaming one another and blaming Aaron but never blaming themselves. Moses therefore sought to unite the Children of Israel here by assembling and connecting them with each other thorough G-ds commands. He again asks the children of Israel to bring an offering to G-d. Among the offerings are: gold, silver, copper, blue, purple and dark red wool, fine twined linen, goats hair, seal-skins, acacia wood, oil for the light, spices for the anointing oils and onyx stones for the ephod or breastplate. Every man and woman of the Children of Israel whose heart stirred them to give, dedicated their offering to G-d and the construction of the Tabernacle.