Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
KINGSLEY DOUGLAS A
  2. Issuer Name and Ticker or Trading Symbol
Proto Labs Inc [PRLB]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
C/O NORTH BRIDGE GROWTH EQUITY, 950 WINTER STREET, SUITE 4600
3. Date of Earliest Transaction (Month/Day/Year)
08/22/2012
(Street)

WALTHAM, MA 02454
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 08/22/2012   J(1)   4,976 A $ 0 4,976 D  
Common Stock               4,821,790 I By North Bridge Growth Equity I, L.P. (2)

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
KINGSLEY DOUGLAS A
C/O NORTH BRIDGE GROWTH EQUITY
950 WINTER STREET, SUITE 4600
WALTHAM, MA 02454
  X      

Signatures

 /s/ Julie M. Regnier, Attorney-in-Fact for Douglas Kingsley   08/24/2012
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) The transaction reported on this Form 4 represents a pro rata distribution, and not a purchase or sale of securities, by North Bridge Growth Equity I, L.P. to Douglas Kingsley without consideration. Mr. Kingsley is a director of Proto Labs, Inc. (the "Issuer") and filed joint Section 16 reports with NBGE Manager, LLC ("NBGE"), NBGE GP, LLC, North Bridge Growth Management, L.P. and North Bridge Growth Equity I, L.P. with the SEC on February 23, 2012 and March 1, 2012 pursuant to which it was reported that North Bridge Growth Equity I, L.P. beneficially held 5,991,790 shares of the Issuer's common stock acquired upon conversion of the Issuer's Series A Preferred Stock, and in which reports Mr. Kingsley disclaimed any beneficial ownership of these shares except to the extent of his pecuniary interest therein.
(2) Represents shares held directly by North Bridge Growth Equity I, L.P. NBGE is the managing manager of NBGE GP, LLC, which is the sole general partner of North Bridge Growth Management, L.P., which is the sole general partner of North Bridge Growth Equity I, L.P. NBGE has sole vesting and dispositive power over such shares. Mr. Kingsley, a director of the Issuer, is a founding managing director of NBGE GP, LLC. Shared voting and investment power over such shares is vested in the managers of NBGE, Edward Anderson and Richard D'Amore. Mr. Kingsley disclaims any beneficial ownership of such shares, except to the extent of any pecuniary interest therein. This report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.

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