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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                            ------------------------

                                  SCHEDULE TO
                                 (RULE 14D-100)
           TENDER OFFER STATEMENT UNDER SECTION 14(D)(1) OR 13(e)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934
                               (AMENDMENT NO. 3)
                                DTM CORPORATION
                       (NAME OF SUBJECT COMPANY (ISSUER))

                               TIGER DEALS, INC.
                             3D SYSTEMS CORPORATION
                                   (OFFERORS)

                   COMMON STOCK, $0.0002 PAR VALUE PER SHARE
                         (TITLE OF CLASS OF SECURITIES)

                                  23333 L 103
                     (CUSIP NUMBER OF CLASS OF SECURITIES)
                            ------------------------


                                                 
                                                                         COPY TO:
                 E. JAMES SELZER                                  JULIE M. KAUFER, ESQ.
           CHIEF FINANCIAL OFFICER AND                  AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.
            VICE PRESIDENT OF FINANCE                             2029 CENTURY PARK EAST
              3D SYSTEMS CORPORATION                                    SUITE 2400
                26081 AVENUE HALL                             LOS ANGELES, CALIFORNIA 90067
            VALENCIA, CALIFORNIA 91355                                (310) 229-1000
                  (661) 295-5600


 (NAME, ADDRESS, AND TELEPHONE NUMBER OF PERSONS AUTHORIZED TO RECEIVE NOTICES
                AND COMMUNICATIONS ON BEHALF OF FILING PERSONS)
                            ------------------------

                           CALCULATION OF FILING FEE



              TRANSACTION VALUATION*                              AMOUNT OF FILING FEE**
              ----------------------                              ----------------------
                                                 
                    $46,971,196                                           $9,395


 *   Estimated for purposes of calculating the filing fee only. Calculated based
     on the product of $5.80, the per share tender offer price for all the
     outstanding shares of common stock, par value $0.0002 per share, of DTM
     Corporation (the "Common Shares"), multiplied by 8,098,482 (which includes
     977,493 shares issuable pursuant to the exercise of outstanding stock
     options).

**  The amount of the filing fee, calculated in accordance with Rule 0-11(d) of
    the Securities Exchange Act of 1934, as amended, equals 1/50 of one percent
    of the aggregate value of cash offered by Tiger Deals, Inc. for such number
    of Common Shares.

[X]  Check the box if any part of the fee is offset as provided by Rule
     0-11(a)(2) and identify the filing with which the offsetting fee was
     previously paid. Identify the previous filing by registration statement
     number, or the Form or Schedule and the date of its filing.


                                                                         
   Amount Previously Paid.  $9,395                       Filing Party...........  Tiger Deals, Inc. and
                                                                                  3D Systems Corporation
   Form or Reg. No. ......  Schedule TO                  Date Filed.............  April 30, 2001
                            Amend. No. 1 to Schedule TO                           May 16, 2001


     [ ]  Check the box if the filing relates solely to preliminary
          communications made before the commencement of a tender offer.

     [X]  third-party tender offer subject to Rule 14d-1.

     [ ]  issuer tender offer subject to Rule 13e-4.

     [ ]  going-private transaction subject to Rule 13e-3.

     [ ]  amendment to Schedule 13D under Rule 13d-2.

     Check the following box if the filing is a final amendment reporting the
results of the tender offer:  [ ]
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     This Amendment No. 3 amends and supplements the Tender Offer Statement on
Schedule TO filed with the SEC on April 30, 2001, as amended and supplemented by
Amendment No. 1 filed with the SEC on May 16, 2001 and Amendment No. 2 filed
with the SEC on May 22, 2001, relating to the offer to purchase by Tiger Deals,
Inc., or "Offeror," a Delaware corporation and an indirect wholly-owned
subsidiary of 3D Systems Corporation, or "Parent," a Delaware corporation, all
of the outstanding shares of common stock, par value $0.0002 per share, of DTM
Corporation, or the "Company," a Texas corporation, at a purchase price of $5.80
per share, net to the seller in cash, without interest and less any required
withholding taxes, upon the terms and subject to the conditions set forth in the
"Offer to Purchase," dated April 30, 2001, the "Amendment and Supplement to
Offer to Purchase," dated May 15, 2001, and in the related Letter of
Transmittal. Copies of the Offer to Purchase, Amendment and Supplement to Offer
to Purchase and Letter of Transmittal were filed as Exhibits (a)(1)(i),
(a)(1)(ix) and (a)(1)(ii), respectively, to the Schedule TO, as amended.
Capitalized terms used herein but not otherwise defined have the meanings
ascribed to those terms in the Offer to Purchase.

     The information in the Schedule TO, as amended, is hereby expressly
incorporated herein by reference in response to all the items of this Amendment
No. 3, except as otherwise set forth below. You should read this amendment
together with the Schedule TO we filed on April 30, 2001, the Amendment No. 1 to
Schedule TO we filed on May 16, 2001 and the Amendment No. 2 to Schedule TO we
filed on May 22, 2001.

ITEM 1. SUMMARY TERM SHEET.

     Item 1 of Schedule TO is hereby amended and supplemented by including the
following:

     On May 24, 2001, we extended the offer until 12:00 midnight, New York City
time, on Thursday, June 7, 2001. The full text of the press release we issued on
May 25, 2001 announcing the extension of the offer is filed as Exhibit
(a)(1)(xi) hereto.

ITEM 4. TERMS OF THE TRANSACTION.

     Item 4 of Schedule TO is hereby amended and supplemented by including the
following:

     On May 24, 2001, we extended the offer until 12:00 midnight, New York City
time, on Thursday, June 7, 2001. The full text of the press release we issued on
May 25, 2001 announcing the extension of the offer is filed as Exhibit
(a)(1)(xi) hereto.

ITEM 11. ADDITIONAL INFORMATION.

     Item 11 of Schedule TO is hereby amended and supplemented by including the
following:

     On May 24, 2001, we received a request from the United States Department of
Justice to extend the offer in order for the Department of Justice to complete
its inquiry into the offer and subsequent merger. In response to the Department
of Justice's request, we agreed to extend the offer until 12:00 midnight, New
York City time, on Thursday, June 7, 2001. The full text of the press release we
issued on May 25, 2001 announcing the extension of the offer is filed as Exhibit
(a)(1)(xi) hereto.

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ITEM 12. EXHIBITS.

                                 EXHIBIT INDEX



  EXHIBIT
   NUMBER                             DESCRIPTION
  -------                             -----------
           
(a)(1)(i)     Offer to Purchase, dated as of April 30, 2001.*
(a)(1)(ii)    Letter of Transmittal for Common Stock.*
(a)(1)(iii)   Notice of Guaranteed Delivery for Common Stock.*
(a)(1)(iv)    Letter to Brokers, Dealers, Commercial Banks, Trust
              Companies and Other Nominees.*
(a)(1)(v)     Letter to Clients from Brokers, Dealers, Commercial Banks,
              Trust Companies and Other Nominees.*
(a)(1)(vi)    Guidelines for Certification of Taxpayer Identification
              Number on Substitute Form W-9.*
(a)(1)(vii)   Text of Joint Press Release issued by the Company and Parent
              on April 3, 2001 (incorporated by reference to Exhibit 99.1
              to Parent's Form 8-K filed April 10, 2001).
(a)(1)(viii)  Summary advertisement published in The Wall Street Journal
              on April 30, 2001.*
(a)(1)(ix)    Amendment and Supplement to Offer to Purchase, dated as of
              May 15, 2001.**
(a)(1)(x)     Text of Press Release issued by the Parent on May 21,
              2001.***
(a)(1)(xi)    Text of Press Release issued by the Parent on May 25, 2001.
(a)(2)        Not applicable.
(a)(3)        Not applicable.
(a)(4)        Not applicable.
(a)(5)        Not applicable.
(b)           Commitment Letter, dated as of April 24, 2001, by U.S. Bank
              National Association and Parent.*
(b)(1)        Loan and Security Agreement, dated as of May 21, 2001, by
              and among U.S. Bank National Association, Parent and other
              signatories.***
(d)(1)        Agreement and Plan of Merger, dated as of April 2, 2001, by
              and among the Company, Parent and Offeror (incorporated by
              reference to Exhibit 99.2 to Parent's Schedule TO-C filed
              April 3, 2001).
(d)(2)        Amendment No. 1 to Agreement and Plan of Merger, dated as of
              May 15, 2001, by and among the Company, Parent and
              Offeror.**
(d)(3)        Form of Tender and Voting Agreement, dated as of April 2,
              2001, by and among Parent, Offeror and certain stockholders
              of the Company (incorporated by reference to Exhibit 99.3 to
              Parent's Schedule TO-C filed April 3, 2001).
(g)           None.
(h)           None.


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  * Previously filed on Schedule TO filed with the SEC on April 30, 2001.

 ** Previously filed on Amendment No. 1 to Schedule TO filed with the SEC on May
    16, 2001.

*** Previously filed on Amendment No. 2 to Schedule TO filed with the SEC on May
    22, 2001.

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                                   SIGNATURE

     After due inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

Dated: May 25, 2001                       TIGER DEALS, INC.

                                          By:      /s/ E. JAMES SELZER
                                            ------------------------------------
                                              Name: E. James Selzer
                                              Title: Chief Financial Officer
                                                     and Vice President, Finance

     After due inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

Dated: May 25, 2001                       3D SYSTEMS CORPORATION

                                          By:      /s/ E. JAMES SELZER
                                            ------------------------------------
                                              Name: E. James Selzer
                                              Title: Chief Financial Officer
                                                     and Vice President, Finance

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                                 EXHIBIT INDEX



  EXHIBIT
   NUMBER                             DESCRIPTION
  -------                             -----------
           
(a)(1)(i)     Offer to Purchase, dated as of April 30, 2001.*
(a)(1)(ii)    Letter of Transmittal for Common Stock.*
(a)(1)(iii)   Notice of Guaranteed Delivery for Common Stock.*
(a)(1)(iv)    Letter to Brokers, Dealers, Commercial Banks, Trust
              Companies and Other Nominees.*
(a)(1)(v)     Letter to Clients from Brokers, Dealers, Commercial Banks,
              Trust Companies and Other Nominees.*
(a)(1)(vi)    Guidelines for Certification of Taxpayer Identification
              Number on Substitute Form W-9.*
(a)(1)(vii)   Text of Joint Press Release issued by the Company and Parent
              on April 3, 2001 (incorporated by reference to Exhibit 99.1
              to Parent's Form 8-K filed April 10, 2001).
(a)(1)(viii)  Summary advertisement published in The Wall Street Journal
              on April 30, 2001.*
(a)(1)(ix)    Amendment and Supplement to Offer to Purchase, dated as of
              May 15, 2001.**
(a)(1)(x)     Text of Press Release issued by the Parent on May 21,
              2001.***
(a)(1)(xi)    Text of Press Release issued by the Parent on May 25, 2001.
(a)(2)        Not applicable.
(a)(3)        Not applicable.
(a)(4)        Not applicable.
(a)(5)        Not applicable.
(b)           Commitment Letter, dated as of April 24, 2001, by U.S. Bank
              National Association and Parent.*
(b)(1)        Loan and Security Agreement, dated as of May 21, 2001, by
              and among U.S. Bank National Association, Parent and other
              signatories.***
(d)(1)        Agreement and Plan of Merger, dated as of April 2, 2001, by
              and among the Company, Parent and Offeror (incorporated by
              reference to Exhibit 99.2 to Parent's Schedule TO-C filed
              April 3, 2001).
(d)(2)        Amendment No. 1 to Agreement and Plan of Merger, dated as of
              May 15, 2001, by and among the Company, Parent and
              Offeror.**
(d)(3)        Form of Tender and Voting Agreement, dated as of April 2,
              2001, by and among Parent, Offeror and certain stockholders
              of the Company (incorporated by reference to Exhibit 99.3 to
              Parent's Schedule TO-C filed April 3, 2001).
(g)           None.
(h)           None.


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  * Previously filed on Schedule TO filed with the SEC on April 30, 2001.

 ** Previously filed on Amendment No. 1 to Schedule TO filed with the SEC on May
    16, 2001.

*** Previously filed on Amendment No. 2 to Schedule TO filed with the SEC on May
    22, 2001.

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