Unity from joining the particulars

עוד במד' קיטון א' עשו לי כו' דכתיב וזאת התרומה.

Further, in the Midrash: "Make Me one small chamber (kiton)..." as it is written, "And this is the terumah (offering)" (Shemos 25:3).

The Sefas Emes cites a Midrash on Hashem's request that Bnei Yisrael make Him a single dwelling-chamber, the Mishkan, beginning with the listing of the materials of the terumah.

וחושב י"ג מינים.

And it enumerates thirteen kinds [of materials].

The pesukim list thirteen separate types of donated materials — gold, silver, copper, and so on.

ומ"מ נק' אחד כי אלה הפרטים הם כללות כל הפרטים ומתחברין להיות א'.

And nevertheless it is called "one," for these particulars are the totality of all the particulars, and they join together to become one.

Though made of thirteen distinct materials, the terumah is called a single offering, because these details encompass all details and unite into one whole.

שיש א' בפ"ע.

For there is a "one" that stands by itself.

There is one kind of oneness that is simply a single, solitary thing on its own.

ויש אחדות הבא מתוך התאחדות הפרטים.

And there is a unity (achdus) that comes from the joining together of the particulars.

But there is a higher oneness — an achdus produced when many separate parts unite into a single integrated whole.

ולכן בכ"מ שמבטלין הכל להשורש ודבוק באחדות יש השראת אחד המיוחד ב"ה וב"ש. ודו"ק:

Therefore, in every place where everything is nullified to its root and cleaves to unity, there is an indwelling of the singular One, blessed be He and blessed be His Name — contemplate this well.

Wherever the many parts are nullified back to their common root and bound together in achdus, the presence of the unique One, Hashem, comes to rest — which is why the Mishkan's many materials, unified, became a dwelling for the Shechinah.

Summary: Though the terumah for the Mishkan consisted of thirteen distinct materials, it is called "one," because there is a higher form of oneness — not a single solitary thing, but the achdus that arises when many particulars are bound into one whole. Wherever the many are nullified to their root and joined in unity, the presence of the singular Hashem comes to rest.