Exhibit 10.2

November 30, 2021

Atlantic Coastal Acquisition Corp.
6 St Johns Lane, Floor 5
New York, New York 10013

Essentium, Inc.
19025 N Heatherwilde Blvd, Suite 100
Pflugerville, TX 78660

BTIG, LLC
65 E 55th Street
New York, New York 10022

Re: Sponsor Letter Agreement

Ladies and Gentlemen:

This letter (this “Letter Agreement”) is being delivered to you in accordance with that certain Business Combination Agreement (the “Business Combination Agreement”), dated as of November 30, 2021, by and among Atlantic Coastal Acquisition Corp., a Delaware corporation (the “ACAH”), Essentium, Inc., a Delaware corporation (the “Company”), and Alpha Merger Sub 1, Inc., a Delaware corporation and wholly-owned subsidiary of ACAH (“Merger Sub”) and hereby amends an restates in its entirety that certain letter (the “Prior Letter Agreement”), dated as of March 3, 2021, by and among Atlantic Coastal Acquisition Management, LLC (the “Sponsor”) and each of Shahraab Ahmad, Burt Jordan, Anthony D. Eisenberg, Ronald C. Warrington, Ned Sizer, Joanna Lord, Bryan Dove, Iqbaljit Kahlon, and Daniel M. Tapiero, who are members of the board of directors and/or management team of ACAH (collectively, the “Insiders”). Capitalized terms used herein are defined in paragraph 15. Capitalized terms used herein but not defined shall have their respective meanings set forth in the Business Combination Agreement.

In order to induce the Company and ACAH to enter into the Business Combination Agreement and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, each of the Sponsor, the Insiders, and Atlantic Coastal Finance Company LLC, a Delaware limited liability company (“ACF” and collectively, the “ACAH Insiders”), hereby agrees with ACAH, BTIG, LLC (“BTIG”) and, at all times prior to any termination of the Business Combination Agreement, the Company as follows:

(a) to approve and adopt the Business Combination Agreement and the Transactions;

(b) in any other circumstances upon which a consent or other approval is required under the Governing Documents of ACAH or otherwise sought with respect to the Business Combination Agreement or the Transactions, to vote, consent or approve (or cause to be voted, consented or approved) all of such ACAH Insiders’ Subject Shares held at such time in favor thereof;

(c) to approve and adopt any proposal to adjourn or postpone such meeting of the stockholders of ACAH to a later date if there are not sufficient votes to adopt the Business Combination Agreement and/or if there are not sufficient shares present in person or by proxy at such meeting of the stockholders of ACAH to constitute a quorum; provided that, in no event shall the ACAH Insiders be required to adjourn a meeting of the stockholders of ACAH to a date that is beyond the Termination Date;

(d) against and withhold consent with respect to any merger, consolidation, tender or exchange offer, reorganization, recapitalization, liquidation, purchase, sale or transfer of all or substantially all of ACAH’s or its Subsidiaries’ assets or securities, or other business combination transaction or acquisition proposal (other than the Business Combination Agreement and the Transactions); and

(e) against any proposal, action or agreement that would (A) impede, interfere with, delay, postpone, discourage, frustrate, adversely affect, prevent or nullify any provision of this Letter Agreement, the Business Combination Agreement, or the Transactions (including the economic benefits to the Company, ACAH and Merger Sub of the Transactions), (B) result in a breach in any respect of any covenant, representation, warranty or any other obligation or agreement of ACAH under the Business Combination Agreement, (C) result in any of the conditions set forth in Article 6 of the Business Combination Agreement not being fulfilled, (D) result in a breach of (i) any covenant, representation or warranty or other obligation or agreement of such ACAH Insider contained in this Agreement, or (ii) ACAH contained in the Business Combination Agreement, or (E) that is otherwise inconsistent with this Agreement, the Business Combination Agreement or the Transactions.

Any vote cast pursuant to this paragraph 1 shall be cast, or consent shall be given, in accordance with such procedures relating thereto as shall ensure that it is duly counted for purposes of determining that a quorum is present and for purposes of recording in accordance herewith the results of such vote or consent. Each ACAH Insider hereby agrees that it shall not commit or agree to take any action inconsistent with the foregoing.

(a) If such ACAH Insider is not an individual, it is duly organized, validly existing and in good standing under the Laws of the jurisdiction in which it is incorporated, formed, organized or constituted, and the execution, delivery and performance of this Letter Agreement and the consummation of the transactions contemplated hereby are within such ACAH Insider’s corporate, limited liability company or organizational powers, have been duly authorized by all necessary corporate, limited liability company or organizational actions on the part of such ACAH Insider and no other corporate, limited liability company or organizational actions on the part of such ACAH Insider are necessary to approve this Agreement or to consummate the transactions contemplated hereby. If such ACAH Insider is an individual, such ACAH Insider has full legal capacity, right and authority to execute and deliver this Agreement and to perform his or her obligations hereunder. This Letter Agreement has been duly executed and delivered by such ACAH Insider and, assuming due authorization, execution and delivery by the other parties to this Agreement, this Letter Agreement constitutes a legally valid and binding obligation of such ACAH Insider, enforceable against such ACAH Insider in accordance with the terms hereof (except as enforceability may be limited by bankruptcy Laws, other similar Laws affecting creditors’ rights and general principles of equity affecting the availability of specific performance and other equitable remedies). If this Letter Agreement is being executed in a representative or fiduciary capacity, the Person signing this Agreement has full power and authority to enter into this Agreement on behalf of the applicable ACAH Insider.

(b) Except as otherwise set forth on Schedule I, such ACAH Insider is the sole record and Beneficial Owner of, has dispositive power over, good title to, and, in the case of the Subject Shares has voting power (including, without limitation, by proxy or power of attorney) over, all of such ACAH Insider’s Subject Shares indicated opposite such ACAH Insider’s name on Schedule I attached hereto, and there exist no Liens or any other limitation or restriction (including any restriction on the right to vote, sell or otherwise dispose of such Subject Shares (other than transfer restrictions under the Securities Act)) affecting any such Subject Shares, other than Liens pursuant to (i) this Letter Agreement, (ii) ACAH’s Governing Documents, (iii) the Business Combination Agreement and any other agreements contemplated thereunder, (iv) the Loan Agreement, or (v) any applicable securities Laws. Except as set forth in the Loan Agreement, such ACAH Insider’s Subject Shares are the only equity securities in ACAH owned of record or Beneficially Owned by such ACAH Insider on the date of this Letter Agreement, and none of such ACAH Insider’s Subject Shares are subject to any proxy, voting trust or other agreement or arrangement restricting or otherwise relating to the voting or Transfer of such Subject Shares. Except as listed on Schedule I and the Loan Agreement, such ACAH Insider does not hold or own any rights to acquire (directly or indirectly) any equity securities of ACAH or any equity securities convertible into, which can be exchanged for, or which will affect the Beneficial Ownership of the ACAH Insider’s interest in, equity securities of ACAH. Such ACAH Insider has not appointed or granted any proxy or power of attorney that is still in effect with respect to any Subject Shares.

(c) The execution and delivery of this Letter Agreement by such ACAH Insider does not, and the performance by such ACAH Insider of his, her or its obligations hereunder will not, (i) if such ACAH Insider is not an individual, conflict with or result in a violation of the Governing Documents of such ACAH Insider, (ii) conflict with or violate any Law applicable to such ACAH Insider or by which any of such ACAH Insider’s assets or properties is bound, (iii) breach, violate, result in the loss of any benefit under, constitute a default under (or an event which with notice or lapse of time or both would become a default), result in the termination of or a right of termination, vesting, cancellation, amendment, notification, purchase or sale under, or result in the creation, acceleration or change of any rights or obligations of any party or the creation of any Lien upon any of the Subject Shares under, any Contract that is binding on the ACAH Insider or any of his assets or properties, or (iv) require any consent, approval, authorization, or permit that has not been given or other action that has not been taken by any Person (including under any Contract binding upon such ACAH Insider or such ACAH Insider’s Subject Shares) to the extent such consent, approval, authorization, permit or other action would prevent, enjoin or materially delay the performance by such ACAH Insider of its, his or her obligations under this Agreement.

(d) There are no Proceedings or Orders pending against, or to the knowledge of such ACAH Insider threatened against or affecting, such ACAH Insider, which (i) in any manner challenges or seeks to prevent, enjoin or materially delay the performance by such ACAH Insider of its, his or her obligations under this Letter Agreement, or (ii) could reasonably be expected to impair or adversely affect the ability of such ACAH Insider to perform its, his or her obligations under this Letter Agreement.

(e) Such ACAH Insider is a sophisticated stockholder and has adequate information concerning the business and financial condition of ACAH and the Company to make an informed decision regarding this Letter Agreement and the Transactions and has independently and without reliance upon ACAH or the Company and based on such information as such ACAH Insider has deemed appropriate, made its own analysis and decision to enter into this Agreement. Such ACAH Insider acknowledges that ACAH and the Company have not made and do not make any representation or warranty, whether express or implied, of any kind or character except as expressly set forth in this Agreement. Such ACAH Insider acknowledges that the agreements contained herein with respect to the Subject Shares held by such ACAH Insider are irrevocable.

(f) Except as set forth in the Business Combination Agreement, including any schedule thereto, no broker, finder, investment banker or other Person is entitled to any brokerage fee, finders’ fee or other commission in connection with the transactions contemplated by the Business Combination Agreement based upon arrangements made by such ACAH Insider in his, her or its capacity as a stockholder or, to the knowledge of such ACAH Insider, on behalf of such ACAH Insider in his, her or its capacity as a stockholder, for which the ACAH Insider or any of its Affiliates may become liable.

(g) Such ACAH Insider understands and acknowledges that each of ACAH and the Company is entering into the Business Combination Agreement in reliance upon such ACAH Insider’s execution and delivery of this Agreement and the representations and warranties, covenants and other agreements of the ACAH Insider contained herein.

(a) The Sponsor and each ACAH Insider agrees that it, he or she shall not Transfer any Private Placement Warrants (or shares of Common Stock issued or issuable upon the exercise of the Private Placement Warrants), until 30 days after the completion of the Transactions (the “Private Placement Warrants Lock-up Period”).

(b) Notwithstanding the provisions set forth in paragraph 13(a), Transfers of the Private Placement Warrants and shares of Common Stock issued or issuable upon the exercise or conversion of the Private Placement Warrants and that are held by the Sponsor, any ACAH Insider or any of their permitted transferees (that have complied with this paragraph 13(b)), are permitted (a) to any persons (including their affiliates and members) participating in the private placement of the Private Placement Warrants; (b) to the Company’s founders, or to the Company’s officers, directors and employees; (c) in the case of an entity, as a distribution to its, partners, stockholders or members upon its liquidation; (d) by bona fide gift to a member of the holder’s immediate family or to a trust, the beneficiary of which is a member of the holder’s immediate family, for estate planning purposes; (e) by virtue of the laws of descent and distribution upon death; (f) pursuant to a qualified domestic relations order; (g) by certain pledges to secure obligations incurred in connection with purchases of the Company’s securities; (h) by private sales or transfers at prices no greater than the price at which the securities were originally purchased; or (i) to the Company for no value for cancellation in connection with the completion of the Transactions; provided, that, in the case of clauses (a) through (h), any such transferees enter into a written agreement with the Company agreeing to be bound by the transfer restrictions in this Letter Agreement.

(a) “Beneficial Ownership” shall be interpreted in accordance with the term “beneficial owner” as defined in Rule 13d-3 adopted by the SEC under the Exchange Act; provided that, notwithstanding the generality of the foregoing, for purposes of determining Beneficial Ownership, a Person shall be deemed to be the Beneficial Owner of any securities which such Person has the right to acquire pursuant to any agreement, arrangement or understanding or upon the exercise of conversion rights, exchange rights, warrants or options, or otherwise (irrespective of whether the right to acquire such securities is exercisable immediately or only after the passage of time, including the passage of time in excess of sixty (60) days, the satisfaction of any conditions, the occurrence of any event or any combination of the foregoing). The terms “Beneficial Ownership,” “Beneficially Own” and “Beneficially Owned” shall have a correlative meaning.

(b) “Common Stock” means the Company’s Class A common stock, par value $0.0001 per share.

(c) “Founder Shares” means the 8,625,000 shares of the Company’s Class B common stock, par value $0.0001 per share, initially issued to the Sponsor.

(d) “Parties” means the ACAH Insiders, ACAH, BTIG, and the Company.

(e) “Private Placement Warrants” means the warrants to purchase up to 6,066,667 shares of Common Stock that the Sponsor purchased for an aggregate purchase price of $9,100,000, or $1.50 per warrant, in a private placement that occurred simultaneously with the consummation of the underwritten initial public offering of the Company’s units.

(f) “Subject Shares” means, with respect to an ACAH Insider, the ACAH Common Shares and ACAH Warrants as are indicated opposite such ACAH Insider’s name on Schedule I attached hereto, together with any ACAH Common Shares of which ownership of (i) record and Beneficial Ownership, (ii) the power to vote (including, without limitation, by proxy or power of attorney) or (iii) any dispositive power, is hereafter acquired by such ACAH Insider during the Term.

(g) “Transfer” means means, directly or indirectly, to (i) sell, offer to sell, contract or otherwise agree to sell, transfer, convey, exchange, assign, deposit, hypothecate, loan, pledge, encumber (including creating or incurring any Lien upon), grant any option to purchase or otherwise dispose of or agree to dispose of (including by gift, merger, consolidation by operation of Law or otherwise (including by conversion into securities or other consideration), either voluntarily or involuntarily, or by tendering into any tender or exchange offer), file (or participate in the filing of) a registration statement with the SEC (other than the Registration Statement / Proxy Statement) or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Exchange Act, with respect to any Subject Shares (or any security convertible or exchangeable into Subject Shares), (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any Subject Shares (or any security convertible or exchangeable into Subject Shares), or (iii) enter into any contract, option or other arrangement or understanding, directly or indirectly, to take any of the foregoing actions.

If to ACAH or any ACAH Insider, to:

Atlantic Coastal Acquisition Corp.
6 St Johns Lane
New York, NY 10013

If to BTIG, to:

BTIG, LLC
65 E 55th Street
New York, New York 10022

If to the Company:

Essentium, Inc.
19025 N Heatherwilde Blvd, Suite 100
Pflugerville, TX 78660

[Signature Page Follows]

[Signature Page to Letter Agreement]

[Signature Page to Letter Agreement]

Schedule I
Beneficial Ownership

Exhibit A
Form of Lock-Up Agreement

(attached hereto)