Building the mishkan was the most holy and intricate task that the Jews were assigned during their sojourn in the desert. Nonetheless, every Friday night all work on this magnificent edifice would come to a grinding halt
The Torah states "work shall be done" -- the passive voice. Becoming so totally devoted to one's job, such that one's work is one's total preoccupation and obsession, is totally unhealthy and an affront to the divine system. You may have to work, but let it be done
The construction was funded by the donations of all the Jews. Men, women and children all lined up to contribute to the cause. One would hardly imagine that the children's gift made much of a difference to a project as grand as that of the Tabernacle...