The obligation to collect donations in order to construct the mishkan (terumat hamishkan) is introduced in Parshat Terumah. The Baal haTurim, noting the Torah's formulation of this charge -"daber el Benei Yisrael ve-yikhu li terumah" - concludes that only Jews were qualified to participate in this particular collection. [His halakhic conclusion is supported by the gematria remez that he adduces from these words!]. This ruling requires some clarification in light of the fact that typically mikdash donations are welcomed and certainly accepted from all sources. The Talmud (Arachin 5b) establishes that the bedek habayit contributions of non-Jews are subject to the violation of meilah, as they attain mikdash status. Why, then, should terumat hamishkan, the original and paradigmatic kodashim contribution be restricted exclusively to Jewish donors? While Tur's exclusion of non-Jews from terumat hamishkan is hardly uniformly accepted (see Rinat Yisrael, Shemot 25:2 ), it still commands our attention and demands an explanation. His view likely reflects a singular perspective on terumat hamishkan that transcends this particular application.
Terumat hamishkan was not merely a fund-raiser for a worthy or sanctified cause. There are indications that while the building of the mishkan was indeed somewhat paradigmatic (see Rambam Hilchot Beit haBechirah 1:1), it was also (and particularly the terumat hamishkan process) sui generis. The Torah repeatedly details the specifics of this process, and portrays these contributions as an independent obligation, seemingly distinct from the obligation to build ("ve-asu li mikdash") or sustain (bedek habayit) the mishkan-mikdash. The commandment to collect the materials necessary for the mishkan and to invest them with lishmah and sanctity (see Rash and Ramban, beginning of terumah) reflects the novelty and spiritual ambition of the very notion of a physical abode for the Divine Shechinah that had just been formatively articulated and that was about to be initiated. Despite the impossibility-inconceivability of the goal- as Hashem cannot be physically limited ("shamayim u- shemei shamayim lo yekalkelukaha", Divrei haYamim), Klal Yisrael were tasked precisely to undertake this project, and instructed with great precision how to implement it. At the same time, only a people who had already defied the norms of a spiritual-material dichotomy by elevating and harnessing physicality for spirituality ("vayechezu et HaElokim va-yochlu va-yishtu" Shemot 24:11), by defining their human rationality based on Divine fiat (naaseh ve-nishma), by experiencing gilui Shechinah (including "ro-im et hakolot") and even an extended ascension into the Shechinah, could participate in this groundbreaking endeavor.
Terumat hamishkan, formulated as an independent mitzvah le-shaah, must be perceived in its context. The charge to contribute follows immediately after the pivotal section in the end of parshat Mishpatim in which the Torah records the celebrated phrase "naaseh ve-nishma (Shemot 24:7), describes the sprinkling of the dam haberit (24:8) symbolizing the singular bond between Am Yisrael and Hashem, and chronicles Moshe Rabbeinu's unprecedented 40-day ascension and inimitable bond with the Shechinah (24:12-18). These pesukim-developments provide the background for the very notion of a permanent mishkan, the most ambitious undertaking of hashraat haShechinah. They establish Klal Yisrael's unique credentials to accomplish this intriguing structure, but also may indicate that hashra'at haShechinah in this form is itself a vital expression of this singular brit! [The midrash, beginning of terumah, suggests that the mishkan, which houses the aron brit Hashem, exemplifies the uniqueness of mattan Torah as a transaction-gift in which the purchaser acquires the prior owner together and along with the precious merchandise!] These considerations certainly justify the exclusion of non-Jews from this highly particularistic manifestation.
Moreover, it is conceivable that the unusual and complex formulation of the obligation of terumat hamishkan reflects an additional dimension that particularly exemplifies kedushat Yisrael, as crystallized in the aforementioned brit. Chidushei haGriz (al haTorah, Terumah) notes that the initial emphasis of the verse - "dabeir el Benei Yisrael ve-yikhu li terumah" - defines an obligation that devolves upon the collective Klal Yisrael. The conclusion of the passuk-"me-eit kol ish asher yidvenu libo tik-chu et terumati"- depicts the requirement of voluntary individual donations. He concludes that terumat hamishkan was, indeed, dialectical- comprised of a chovat tzibur that was implemented (kiyum) by voluntary individual donations. Certainly this obligatory national collection of individual donations particularly typifies the brit of naaseh ve-nishma (Shemot 24:3,4,7), the experience of gilui Shechinah at maamad har Sinai (Shemot 20:2,14), and generally characterize the singular halakhic approach to law, life, and kedushah. The interplay between obligation (gadol metzuveh veoseh) and voluntarism (nedavah, lifnim meshurat hadin, zeh keili etc.) is a major theme in halakhic life. The intricate duality of personal and collective-national motifs underpins all of Jewish law and thought. It was surely appropriate that terumat hamishkan, embodying the ambition, vision, expansive methodology, and diverse themes of the brit itself emerge as an independent mitzvah addressed exclusively to Klal Yisrael. It was the necessary and natural bridge to attaining the nearly impossible but absolutely vital timeless goal of "ve-asu li mikdash veshachanti betocham"(25:8.)