Or HaChaim on Exodus 39:43/אור החיים על שמות ל״ט:מ״ג

1 והנה עשו…כן עשו, and behold they had done it…so they had done. The additional word והנה in this verse alludes to the speed with which the Tabernacle was built, something that was very pleasing to Moses when he looked at the components the people presented him with.

2The addition of the word אותה in the line עשו אותה, testifies to the quality of the work. The artisans had put to use all their intelligence in constructing these parts and the result had proved successful.

3If we follow the approach of the Talmud Zevachim 62 that every commandment contains details which are not mandatory but which are desirable, the Torah tells us that the artisans performed even all those details which were not mandatory. This explains why the Torah repeated the word עשו, they did, i.e. the artisans did both what was mandatory and what was in effect optional.

4ויברך אותם משה, Moses blessed them. The reason the Torah wrote the name Moses instead of simply "he blessed them," (seeing that his name was mentioned at the beginning of our verse) is to teach us not to take this blessing lightly. It is something very special to be blessed by a man of G'd such as Moses. If the people had been blessed by someone of lesser stature the Torah would not have recorded this as something we have to know so many thousands of years later. Normally, the Torah could have written משה ברך אותם, or: הוא ברך אותם. By placing the name Moses at the end of the line the Torah taught us the significance of being blessed by someone of Moses' standing.