The builder of the Mishkon was none other than a very young genius named Betzalel, who was only 13 years old at he time. He was a master of every type of craft. This most gifted child was a pure genius in every sense of the word. He showed brilliant skill in everything he touched. He was an expert at building anything.
However, his knowledge was much greater that just building. The Gemorah in Brochos says that he understood the very secrets of creation. He understood how the letters of the Torah could be put together to create anything in the universe Betzalel knew how to put together the letters with which Hashem created heaven and earth.

In the Gemorah Chagigah (second perek), we are told that the first 42 letters of the Torah contain all the secrets of creation. All the formulas of the 92 elements as well as all else are contained within these 42 letters. Of course, it's done in a scrambled code, and only the greatest chachomim possessing infinite wisdom can decipher it. These secrets were given over from generation to generation, from rebbi to student. It could be taught only to one student at a time. The rebbi had to make sure that the student was an extremely wise one, so that he made no mistake.
The Torah can be compared to the blueprint of a building. Only one who has studied architecture can read all it's details and understand its meaning. To the unlearned it seems only a scribble.
The Torah proceeded the world and it served as the blueprint for its construction. Those great chachomim who know how to read its blueprint are able to understand the great secrets of creation. The names of each of the objects were not picked at random. The letters correspond to its very being. The loshon hakodesh letters represent the formula of the object. The letters Mem-Yud- Mem which stand for water give one all the secrets of its creation and its properties. One must of course know its code. When Odom HaRishon named all the animals and other objects, he didn't just pick the first name that came to his mind. He picked the letters that stood for the secrets of its creation.
Betzalel knew these secrets, therefore he was given the great and important task of building the Mishkon. Betzalel's very name indicated his greatness, for the translation of his name is "in the shadow of G-D." He was so dedicated to serving Hashem that he was comparable to a shadow that is an exact duplicate and replica of the object.
When the wind blows on a tree and its thousands of leaves shake, then their shadow moves exactly in unison and in perfect step with the leaves themselves. It is impossible for the shadow to deviate in the slightest. Every movement of each leaf is exactly duplicated by its shadow. This was Betzalel - an exact duplicate of Hashem's desires. His every move would follow Hashem's desire with the exactness of a shadow following its object. There could be no deviation in the slightest.
Therefore, when Moshe told him the order in which to build the Mishkon he sensed at once that the order was incorrect. A shadow will always follow the object, no matter in which direction it turns. Betzalel could not deviate from Hashem's will even in the slightest.
A shadow is not an entity in itself. It just seems to be there. Yet is it actually totally botel to the object it shadows. Betzalel realized that even though he was one of the greatest geniuses in his generation, it was all really nothing of his own. Every bit of his great talent was only like a shadow. He was a total onov. Can a computer take the credit for solving a difficult problem? Of course not. It is only doing what a human programmed it to do. He knew with complete certainty that all his great talent was nothing but a manifestation of his Creator.
Only one who understands this properly can be chosen as the builder of Hashem's House.
No wonder it was Betzalel that was chosen to build the Mishkon.