POWER OF ATTORNEY

        The undersigned constitutes and appoints each of Ryan Martin, Mark
Frost, Steven J. Gavin, James R. Brown and Luisa F. Patoni, or any of them
signing singly, and with full power of substitution, the undersigned's true and
lawful attorney-in-fact to:

    1.  Prepare, execute in the undersigned's name and on the undersigned's
        behalf, and submit to the U.S. Securities and Exchange Commission (the
        "SEC") a Form ID and the Form ID Confirming Statement, including
        amendments thereto, and any other document necessary or appropriate to
        obtain codes and passwords enabling the undersigned to make electronic
        filings with the SEC of reports required by Section 16(a) of the
        Securities Exchange Act of 1934 or any rule or regulation of the SEC;

    2.  Execute for and on behalf of the undersigned, in the undersigned's
        capacity as an officer and/or director of Fathom Digital Manufacturing
        Corporation (the "Company"), Forms 3, 4 and 5 in accordance with Section
        16(a) of the Securities Exchange Act of 1934 and the rules and
        regulations promulgated thereunder and to file the same with all
        exhibits thereto, and other documents in connection therewith, with the
        SEC, the Company and any stock exchange on which any of the Company's
        securities are listed, granting unto said attorneys-in-fact and agents,
        and each of them, full power and authority to do and perform each act
        and thing requisite and necessary to be done under said Section 16(a),
        as fully and to all intents and purposes as the undersigned might or
        could do in person, hereby ratifying and confirming all that said
        attorneys-in-fact and agents, and each of them, may lawfully do or cause
        to be done by virtue hereof.

    3.  Take any other action of any type whatsoever in connection with the
        foregoing which, in the opinion of such attorney-in-fact, may be of
        benefit to, in the best interest of, or legally required by, the
        undersigned, it being understood that the documents executed by such
        attorney-in-fact on behalf of the undersigned pursuant to this Power of
        Attorney shall be in such form and shall contain such terms and
        conditions as such attorney-in-fact may approve in such attorney-in-
        fact's discretion.

        The undersigned hereby grants to the attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or evocation,
hereby ratifying and confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be
done by virtue of this Power of Attorney and the rights and powers herein
granted. The undersigned acknowledges that the foregoing attorney-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming, any of the undersigned's responsibilities to comply
with Section 16 of the Securities Exchange Act of 1934.

        This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file a Form ID, Forms 3, 4 and 5 with
respect to the undersigned's holdings of and transactions in securities issued
by the Company, unless earlier revoked by the undersigned in a signed writing
delivered to the foregoing attorney-in-fact.

        IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 16th day of December, 2021.

                                        /s/Caralynn Valerie Collens
                                        --------------------------------
                                        Name:  Caralynn Valerie Collens