Exhibit 10.18

                       SENIOR SUBORDINATED PROMISSORY NOTE

$500,000.00                                                      AUGUST 15, 2002
                                                               BOULDER, COLORADO

     FOR VALUE RECEIVED, Avatech Solutions, Inc., a Delaware corporation
("BORROWER"), hereby unconditionally promises to pay to the order of PlanetCAD
Inc., a Delaware Corporation ("LENDER"), in lawful money of the United States of
America and in immediately available funds, the principal sum of $500,000.00 and
any unpaid accrued interest thereon, as set forth below.

     The following is a statement of the rights of Lender under this Senior
Subordinated Promissory Note (this "NOTE") and the conditions to which this Note
is subject, and to which Lender, by the acceptance of this Note, agrees:

     1.   PRINCIPAL REPAYMENT. Lender may require payment of the outstanding
principal amount of this Note at any time beginning on the earlier of (i) the
date on which Borrower becomes unable (whether due to Borrower's inability to
satisfy a closing condition or otherwise) or refuses to close the merger with
Lender contemplated by the merger agreement, as amended, between the parties
dated May 1, 2002 and (ii) July 1, 2003 (either (i) or (ii), the "MATURITY
DATE"). At any time upon prior written notice to Lender, the Borrower may prepay
without penalty, in whole or in part, the principal sum, plus accrued interest
to the date of payment, of this Note.

     2.   INTEREST RATE. Borrower further promises to pay interest on the unpaid
principal balance of this Note, which interest shall accrue at a simple rate of
15.0% per annum beginning on the date hereof. Interest shall be payable on the
Maturity Date or on such earlier date as the entire principal amount shall
become due and payable and shall be calculated on the basis of a 365-day year
for the actual number of days elapsed.

     3.   PLACE OF PAYMENT. All amounts payable hereunder shall be payable to
Lender at the following address: 2520 55th Street, Suite 200, Boulder, CO
80301, Attention: Treasurer

     4.   APPLICATION OF PAYMENTS. All payments on this Note shall first be
applied to accrued interest and thereafter to the outstanding principal balance
hereof.

     5.   DEFAULT.

          5.1  EVENT OF DEFAULT. The occurrence of any one or more of the
following events shall constitute an event of default ("EVENT OF DEFAULT")
hereunder:

          (a)  Failure to pay, when due, the principal, any interest, or any
other sum payable hereunder;

          (b)  The admission by Borrower in writing of its inability to pay its
debts as such debts become due, or the making by Borrower of any general
assignment for the benefit of creditors;

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          (c)  The commencement by Borrower of any case, proceeding, or other
action seeking reorganization, arrangement, adjustment, liquidation,
dissolution, or composition of its debts under any law relating to bankruptcy,
insolvency, or reorganization, or relief of debtors, or seeking appointment of a
receiver, trustee, custodian, or other similar official for it or for all or any
substantial part of its property;

          (d)  The commencement of any case, proceeding, or other action against
Borrower seeking to have any order for relief entered against it as debtor, or
seeking reorganization, arrangement, adjustment, liquidation, dissolution, or
composition of Borrower's debts under any law relating to bankruptcy,
insolvency, reorganization, or relief of debtors, or seeking appointment of a
receiver, trustee, custodian, or other similar official for it or for all or any
substantial part of the property of Borrower, and (i) Borrower, by any act or
omission, indicates its consent to, approval of, or acquiescence in such case,
proceeding, or action, or (ii) such case, proceeding, or action results in the
entry of an order for relief which is not fully stayed within 60 days after the
entry thereof, or (iii) such case, proceeding, or action remains undismissed for
a period of 60 days or more; or

          (e)  Default in the performance of any obligation, covenant or
agreement contained or referred to herein.

          5.2  CONSEQUENCES OF DEFAULT. Upon the occurrence of any Event of
Default, the entire principal amount hereof, and all accrued and unpaid interest
thereon, shall be accelerated, and shall be due and payable, at the option of
Lender, on the fifth day after Lender provides notice of such Event of Default,
provided that such Event of Default is not cured to Lender's satisfaction in
that five-day period, and in addition thereto, and not in substitution therefor,
Lender shall be entitled to exercise any one or more of the rights and remedies
provided by applicable law. Failure to exercise said option or to pursue such
other remedies shall not constitute a waiver of such option or such other
remedies or of the right to exercise any of the same in the event of any
subsequent Event of Default hereunder. Lender shall be entitled to collect all
reasonable costs and expenses of collection and/or suit, including, but not
limited to, reasonable attorneys' fees.

     6.   PRIORITY. All rights and priorities of the authorized holder of this
Note and the indebtedness evidenced hereby shall rank in all respects (i) junior
to Borrower's obligations under that certain Financing Agreement dated October
25, 2000 between The CIT Group/Business Credit, Inc. ("CIT") and Borrower as set
forth in that certain subordination agreement between Lender and CIT dated on or
about the date hereof, (ii) senior to all other indebtedness of the Borrower,
including, without limitation, amounts owed under those obligations known as the
10% Subordinated Notes and (iii) PARI PASSU with the promissory note issued by
Borrower to James Hindman on or about the date hereof (the "HINDMAN NOTE").
Other than the Hindman Note, Borrower shall not incur any indebtedness outside
the ordinary course of business after the date hereof without Lender's prior
written consent.

     7.   WAIVER; AMENDMENT. No delay or omission on the part of the Lender in
the exercise of any right or remedy hereunder shall operate as a waiver thereof,
nor shall any single or partial exercise of any right or remedy preclude any
other or further exercise thereof or the exercise of any other right or remedy.
The Borrower hereby waives demand, presentment and

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protest and notices thereof as well as notice of non-payment. The provisions of
this Note may be amended with the written consent of Borrower and Lender. The
obligations of Borrower and the rights of Lender under this agreement may be
waived by written notice delivered to Borrower.

     8.   EXPENSES. The Borrower agrees to pay on demand all costs and expenses,
including, without limitation, reasonable attorney's fees, incurred by the
Lender in connection with this Note. In addition, the Borrower agrees to pay on
demand all costs and expenses, including, without limitation, reasonable
attorney's fees, incurred by the Lender in endeavoring to enforce the rights of
the Lender hereunder.

     9.   GOVERNING LAW. This Note shall be governed by, and construed and
enforced in accordance with, the laws of the State of Colorado, excluding
conflict of laws principles that would cause the application of laws of any
other jurisdiction.

     10.  ASSIGNMENT. This Note shall inure to the benefit of and be enforceable
by Lender's successors and authorized assigns, and shall be binding and
enforceable against Borrower's successors and assigns.

     IN WITNESS WHEREOF, Borrower has executed this Note as of the date first
written above.


                                    BORROWER
                                    Avatech Solutions, Inc.



                                    By: /s/ Henry D. Felton
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