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EXHIBIT 10.40

August 6, 1993

CIBA-GEIGY Limited
CH-1723 Marly 1, Switzerland
Attention: Dr. Max Hunziker:

R&D Agreement

Dear Sirs:

    The existing modified R&D Agreement shall be further modified as follows:

Paragraph 1.a) "SL-Process" shall mean the StereoLithography method of 3D, as
defined and claimed (i) in the patent or patents now set forth on Annex A as
such patents existed on May 6, 1988, regardless of any subsequent amendments,
modifications or limitations thereof; (ii) in any additional patents or patent
applications (while such applications are pending) added to Annex A at the date
of the agreement or thereafter by mutual consent of the parties, such consent to
be not unreasonably withheld, together with the documented know-how relating to
the claims set forth in such patents or patent applications provided, if such
know-how is outside of the claims set out in such patent on Annex A such
documented know-how shall be described on Annex A, or added thereto with the
mutual consent of the parties, such consent not to be reasonably withheld; and
(iii) any solid imaging process that uses ink jet technology to dispense any
type of initiator or reactive or non-reactive monomer or other solid or
solidifying or supporting material that is used in the formation of
three-dimensional objects.

    The following U.S. Patents shall be added to Annex A:

BI 4,575,330   APPARATUS FOR PRODUCTION OF THREE-DIMENSIONAL OBJECTS BY
STEREOLITHOGRAPHY 4,929,402   METHOD FOR PRODUCTION OF THREE-DIMENSIONAL OBJECTS
BY STEREOLITHOGRAPHY 4,996,010   METHODS AND APPARATUS FOR PRODUCTION OF
THREE-DIMENSIONAL OBJECTS BY STEREOLITHOGRAPHY 4,999,143   METHODS AND APPARATUS
FOR PRODUCTION OF THREE-DIMENSIONAL OBJECTS BY STEREOLITHOGRAPHY 5,015.424  
METHODS AND APPARATUS FOR PRODUCTION OF THREE-DIMENSIONAL OBJECTS BY
STEREOLITHOGRAPHY 5,058,988   APPARATUS AND METHOD FOR PROFILING A BEAM
5,059,021   APPARATUS AND METHOD FOR CORRECTING FOR DRIFT IN PRODUCTION OF
OBJECTS BY STEREOLITHOGRAPHY 5,059,359   METHODS AND APPARATUS FOR PRODUCTION OF
THREE-DIMENSIONAL OBJECTS BY STEREOLITHOGRAPHY 5,071,337   APPARATUS FOR FORMING
A SOLID THREE-DIMENSIONAL ARTICLE FROM A LIQUID MEDIUM (QUADRAX) 5,076,974  
METHODS OF CURING PARTIALLY POLYMERIZED PARTS 5,096,530   RESIN FILM RECOATING
METHOD AND APPARATUS 5,104,592   METHOD OF AND APPARATUS FOR PRODUCTION OF
THREE-DIMENSIONAL OBJECTS BY STEREOLITHOGRAPHY WITH REDUCED CURL 5,123,734  
APPARATUS AND METHOD FOR CALIBRATING AND NORMALIZING A STEREOLITHOGRAPHIC
APPARATUS

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5,130,064   METHOD OF MAKING A THREE-DIMENSIONAL OBJECT BY STEREOLITHOGRAPHY
5,133,987   STEREOLITHOGRAPHIC APPARATUS AND METHOD 5,137,662   METHOD AND
APPARATUS FOR PRODUCTION OF THREE-DIMENSIONAL OBJECTS BY STEREOLITHOGRAPHY
5,141,680   THERMAL STEREOLITHOGRAPHY 5,143,663   STEREOLITHOGRAPHY METHOD AND
APPARATUS 5,164,128   METHODS FOR CURING PARTIALLY POLYMERIZED PARTS 5,174,931  
METHOD OF AND APPARATUS FOR MAKING A THREE-DIMENSIONAL PRODUCT BY
STEREOLITHOGRAPHY 5,174,943   METHOD FOR PRODUCTION OF THREE-DIMENSIONAL OBJECTS
BY STEREOLITHOGRAPHY 5,182,055   METHOD OF MAKING A THREE-DIMENSIONAL OBJECT BY
STEREOLITHOGRAPHY 5,182,056   STEREOLITHOGRAPHY METHOD AND APPARATUS EMPLOYING
VARIOUS PENETRATION DEPTHS 5,182,715   RAPID AND ACCURATE PRODUCTION OF
STEREOLITHOGRAPHIC PARTS 5,184,307   METHOD AND APPARATUS FOR PRODUCTION OF HIGH
RESOLUTION THREE-DIMENSIONAL OBJECTS BY STEREOLITHOGRAPHY 5,192,469  
SIMULTANEOUS MULTIPLE LAYER CURING IN STEREOLITHOGRAPHY 5,192,559   APPARATUS
FOR BUILDING THREE-DIMENSIONAL OBJECTS WITH SHEETS 5,209,878   SURFACE
RESOLUTION IN THREE DIMENSIONAL OBJECTS BY INCLUSION OF THIN FILL LAYERS
5,234,636   METHODS OF COATING STEREOLITHOGRAPHIC PARTS 5,236,677   METHOD AND
APPARATUS FOR PRODUCTION OF THREE DIMENSIONAL OBJECTS BY STEREOLITHOGRAPHY

    We envision a continuing successful R&D program;

Yours truly,

 
   
/s/

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Charles W. Hull
3D Systems, Inc.   /s/

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Arthur B. Sims
3D Systems, Inc.

Agreed and Accepted:.

CIBA-GEIGY Limited

2

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EXHIBIT 10.40