The Talmud recognises that his name means “In the Shadow of God” and speculates as to why the name was appropriate.
When God appointed B’tzalel as architect of the sanctuary He asked Moses if he approved. Moses answered, “If he is acceptable to You, he certainly is to me!”
The lightstand for the Tabernacle seemed very complicated to Moses, though God twice showed him a model of what He had in mind – but to B’tzalel the message came across at once and he set about turning the designs into reality without delay. Moses was so impressed that he said in admiration that B’tzalel really was “in the shadow of God”.
How old B’tzalel was at the time is given in a Talmudic text (Sanh. 69b) which suggests that he was only 13.
No-one is ever too young or too old, in the view of Jewish teaching, to achieve wonders. A B’tzalel at 13 can build a Temple; a Moses at 120 can still lead the people with energy. Discrimination on the grounds of age was never a good idea. It is unlawful in many countries but in practice it is still hard to become accepted if you are allegedly too young or too old. A society that imposes age barriers is depriving itself of potentially valuable achievements.