mitzvos as a national mandate

 וַתֵּ֕כֶל כׇּל־עֲבֹדַ֕ת מִשְׁכַּ֖ן אֹ֣הֶל מוֹעֵ֑ד וַֽיַּעֲשׂוּ֙ בְּנֵ֣י יִשְׂרָאֵ֔ל כְּ֠כֹ֠ל אֲשֶׁ֨ר צִוָּ֧ה ה׳ אֶת־מֹשֶׁ֖ה כֵּ֥ן עָשֽׂוּ׃  At first glance it seems that the pasuk here (39:32) is backwards.  First it should tell us that the people did the work, וַֽיַּעֲשׂוּ֙ בְּנֵ֣י יִשְׂרָאֵ֔ל ..., and then tell us that they completed the job, וַתֵּ֕כֶל כׇּל־עֲבֹדַ֕ת מִשְׁכַּ֖ן .  Instead, it first tells us that they finished the job and only then tells us that the people did the work!  

Some of the meforshei Rashi write that this is the difficulty Rashi is trying to address in his short cryptic comment ויעשו בני ישראל – את המלאכה.

The Oznayim laTorah offers a different answer, but before getting to it, I want to point out the Ohr haChaim's comment to the pasuk and then come back and combine the two.  Ohr haChaim writes that in fact it was not everyone who participated in the work on the mishkan.  It was Betzalel and the artisans who did the work.  However, the pasuk credits everyone -- וַֽיַּעֲשׂוּ֙ בְּנֵ֣י יִשְׂרָאֵ֔ל.  He explains:

 והוא מה שאמר הכתוב כאן ויעשו בני ישראל ככל אשר צוה ה׳ כינה לכולם יחד מעשה כולם הגם שמהם הביאו הנדבה מהם עשו מלאכה יאמר על כללותם שעשו הכל

This is not just a din in shlucho shel adam k'moso (which he suggests at the start of his explanation), but is a different principle entirely.  

עוד נראה כי כאן עשה הכתוב מחברת הכללות בקיום התורה והראה כי בני ישראל יזכו זה לזה והתורה נתנה להתקיים בכללות ישראל כל אחד יעשה היכולת שבידו ויזכו זה לזה. ואולי כי לזה רמז באומרו (ויקרא י״ט י״ח) ואהבת לרעך כמוך, פירוש לצד שהוא כמותך כי בשלומו ייטיב לך ובאמצעותו אתה משלים שלימותך ואם כן אינו אחר אלא אתה עצמך וכאחד מחלקיך.

ובזה מצאנו נחת רוח כי ה׳ צוה תרי״ג מצות ומן הנמנע שימצא אדם אחד שישנו בקיום כולם וזה לך האות כהן ולוי וישראל ונשים, יש מצות עשה בכהנים שאין מציאות לישראל לעשותם, ויש מצות לישראל שאינם בכהנים, וכן בלוים, וכן בנשים, ומה מציאות יש ליחיד לקיימם להשלים תיקון לרמ״ח איבריו ושס״ה גידיו אשר יכוונו להם, אלא ודאי שתתקיים התורה במחברת הכללות ויזכו זה מזה

What he is saying is that even though particular individuals may have done the work, the nation as a whole gets credit.  You could argue that this is a unique din in making the mishkan because it's a chovas ha'tzibur, but Ohr haChaim generalizes to all mitzvos. No single individual can do all 613 mitzvos, nor is he expected to.  The 613 mitzvos are a mandate to the nation.  The individual gets credit and can accomplish all the mitzvos by virtue of being part of the whole.

Now for the Oznayaim laTorah.  He writes that the second half of the pasuk is not speaking about the mishkan, but is speaking more generally about the observance of any and all mitzvos.  We have a principle that mitzvah goreres mitzvah.  When you do one good thing, you are inclined to do another.  Positive energy begets more positive energy.  The reverse is of course also true.  Once you are on a downward slope, the negative energy reinforces itself.  The cheit ha'eigel was a steep downward drop that sapped the energy and upward momentum out of Bn"Y.  It was the collective effort to build the mishkan, with all the positive energy that went into the many steps to get the job done, that reversed the trend.  Now that that job was complete, וַתֵּ֕כֶל כׇּל־עֲבֹדַ֕ת מִשְׁכַּ֖ן, the momentum was changed and וַֽיַּעֲשׂוּ֙ בְּנֵ֣י יִשְׂרָאֵ֔ל כְּ֠כֹ֠ל אֲשֶׁ֨ר צִוָּ֧ה ה׳ אֶת־מֹשֶׁ֖ה it became easier for Bn"Y to once again do what G-d asked of them.  

Let's maybe put 2 and 2 together. The eigel was not just a tragedy and a failure for the 3000 people who actually committed the sin of idolatry.  It was a tragedy and a failure for the nation as a whole.  The people were now splintered and divided between those like the bnei Levi who were willing to carry out the punishment of misa against their own relatives, and those like the 3000 who had gone and worshipped an eigel.  In a situation like that, even the people who remain loyal to doing Torah and mitzvos do so as individuals, without the centripetal force of a national identity to bind them together.

It was this cohesion that the mishkan restored.  It was not a project of individuals, but it was a collective project of the nation.  It's completion therefore made it easier for us to do mitzvos not just as individuals, but mitzvah goreres mitzvah, to do mitzvos together as a united people.  

This same idea is reflected in the placement of the mitzvah of shabbos.  Terumah/Titzaveh gave us the details of the mishkan, and then in Ki Tisa we have the mitzvah of shabbos, but in VaYakhel, the order is reversed, first comes the mitzvah of shabbos and then the details of the mishkan.  Sefas Emes quotes in the name of the Ch' haRI"M, whose yahrzeit is today, that before cheit ha'eigel we were able to build a mishkan and afterwards have shabbos.  When we get to Vayakhel it's after the cheit, and after the cheit we need shabbos to pull us together first.  We need shabbos to pull us together, to renew our upward momentum as a people, and only then will we have the unity and the ability to make a mishkan.