<PAGE>

                                                                     Exhibit 4.5
                               FIRST AMENDMENT TO

                                    WARRANTS



         This First  Amendment  (this  "AMENDMENT") to Warrants is entered into,
dated and  effective as of August 22, 2003,  among  Stratasys,  Inc., a Delaware
corporation  (the  "COMPANY"),  and each  purchaser  identified on the signature
pages hereto (each, a "PURCHASER" and collectively, the "PURCHASERS").

         WHEREAS,  the Company  and each  Purchaser  is a party to that  certain
Securities  Purchase  Agreement  dated as of  August  22,  2003  (the  "PURCHASE
AGREEMENT");

         WHEREAS,  pursuant to the Purchase Agreement the Company issued to each
Purchaser a Warrant (each a "Warrant" and collectively the "Warrants"); and

         WHEREAS,  the  Company and the  Purchasers  desire to amend each of the
Warrants as set forth herein;

         NOW,  THEREFORE,  IN CONSIDERATION of the mutual covenants contained in
this Agreement,  and for other good and valuable  consideration  the receipt and
adequacy of which are hereby acknowledged, the Company and each Purchaser agrees
to amend each of the Warrants as follows:

         1. Section 11(b) of each of the Warrants is hereby amended and restated
as follows:

                           (b)   Notwithstanding   anything   to  the   contrary
                  contained herein, the maximum number of shares of Common Stock
                  that the Company  shall be  required to issue  pursuant to the
                  Transaction  Documents equals 345,000 shares,  as adjusted for
                  any stock split, subdivision, dividend or distribution payable
                  in  shares of Common  Stock  (or  other  securities  or rights
                  convertible  into, or entitling the holder  thereof to receive
                  directly or indirectly shares of Common Stock),  reverse stock
                  split,  combination or other similar recapitalization or event
                  occurring after August 22, 2003 (the "Issuable Maximum").  If,
                  at the time any  Holder  requests  an  exercise  of any of the
                  Warrants,  the Actual  Minimum  exceeds the Issuable  Maximum,
                  then the  Company  shall issue to the Holder  requesting  such
                  exercise or  conversion a number of shares of Common Stock not
                  exceeding  such  Holder's  pro-rata  portion  of the  Issuable
                  Maximum  (based  on  such  Holder's  share   (vis-a-vis  other
                  Holders)  of the  aggregate  purchase  price  paid  under  the
                  Purchase  Agreement  and taking into  account  any  Underlying
                  Shares previously  issued to such Holder),  this Warrant shall
                  terminate  with respect to such Holder,  and the Company shall
                  have no further obligations to issue shares of Common Stock or
                  otherwise under this Warrant. For the purposes hereof, "Actual
                  Minimum"  shall mean,  as of any date,  the maximum  aggregate
                  number of shares of Common  Stock then  issued or  potentially
                  issuable in the future pursuant to the Transaction



<PAGE>

                  Documents,  including  any  Underlying  Shares  issuable  upon
                  exercise in full of all Warrants, without giving effect to any
                  limits on the  number of  shares of Common  Stock  that may be
                  owned by a Holder at any one time.


         3. None of the Purchasers has  transferred  any interest in the Warrant
issued to it under the Agreement.  The Company shall as soon as possible, and in
any  event  within  3 days  of the  date  hereof,  issue  to  each  Purchaser  a
replacement warrant reflecting the amendment set forth in this Amendment.

         4.  The  Agreement  and  each  of the  Warrants,  as  amended  by  this
Amendment,  shall  continue  to be and shall  remain in full force and effect in
accordance with their respective terms.

         5.  This  Amendment  may be  executed  by  facsimile  in any  number of
counterparts, each of which shall be an original, with the same effect as if the
signatures thereto and hereto were upon the same instrument.


         IN WITNESS WHEREOF, the parties hereto have caused this First Amendment
to the Warrants to be duly executed by their respective  authorized  signatories
as of the date first indicated above.


                                    STRATASYS, INC.


                                    By: /s/ S. Scott Crump
                                        ---------------------------------------
                                        Name: Scott Crump
                                        Title: CEO




                                    CRANSHIRE CAPITAL, L.P.


                                    By: /s/ Mitchell P. Kopin
                                        ---------------------------------------
                                        Name: Mitchell P. Kopin
                                        Title: President - Downsview Capital
                                               The General Partner



                                    SMITHFIELD FIDUCIARY LLC


                                    By: /s/ Adam J. Chill
                                        ---------------------------------------
                                        Name: Adam J. Chill
                                        Title: Authorized Signatory