Foundation for a new covenant

Eph 2:20 is a cessationist prooftext. That, however, raises questions regarding the function of the metaphor in Paul's argument. Metaphors aren't like propositions with logical implications. Metaphors are open-textured, and it's because they can be taken in so many different directions that we need to be sensitive to the intended scope of the metaphor. Failure to confine ourselves to the role which the metaphor was meant to play in an author's argument is a recipe for mischief, nonsense, and heresy (as the case may be). 

What is the author using that to illustrate? In his recent commentary, this is how Baugh construes the imagery:

The point is that the Ephesian congregation has already been laid down as a first layer of stone upon the temple's foundation. From here the building will continue to be erected ("grow," v21), but the foundation and the initial level had already been laid down when Paul wrote this epistle (cf. Rom 15:20; 1 Cor 3:10-14). In the background is the notion that there is no going back to the Mosaic theocracy that excluded Gentiles from full membership in "the covenants of promise" (cf. Gal 2:18). The Mosaic "old covenant" has been displaced by its fulfillment in the "new covenant" definitively and permanently instituted by the once-for-all, high-priestly sacrifice of Christ (e.g., 2 Cor 3:7-11; Heb 7:12; 8:13; 9:15-18; 10:8-12).   

No Ephesian could hear vv21-22 without thinking immediately of the great Temple of Artemis Ephesia (the Artemisium), one of the seven wonders of the ancient world and the largest building in the Greek world. The Artemisium was about four times larger than the Athenian Parthenon. It made Ephesus an important tourist attraction and formed a large part of  its economy (Acts 19:24-27,35), S. M. Baugh, Ephesians (Lexham Press, 2016), 201, 204. 

So according to Baugh's analysis, the purpose of the imagery is, in the first place, to show that the Mosaic theocracy is defunct. You might say that foundation was torn up. Replaced. A new foundation was laid. Ephesian Christians are the first story.

It isn't possible to lay the old covenant onto of the foundation of the new covenant. It can't be relaid. That's out of place. Out of sequence. Anachronistic. Passe.

In addition, although Baugh doesn't make this explicit, Paul may be taking a polemical swipe at the cult of Artemis in Ephesus, by appropriating temple imagery for Christian usage. The spiritual Christian temple displaces the pagan temple.  

In context, I don't think Eph 2:20 can be used as a prooftext for cessationism. That doesn't disprove cessationism. But it must look elsewhere for its exegetical justification.