Proto Labs, Inc. (NYSE: PRLB) announced today the pricing of a follow-on offering of 3.6 million shares of its common stock, of which 3.5 million shares will be sold by certain selling shareholders and 100,000 shares will be sold by Proto Labs, at a price to the public of $31.00 per share. In addition, certain of the selling shareholders have granted the underwriters an option to purchase up to an additional 540,000 shares of common stock. Proto Labs will not receive any of the proceeds from the sale of the shares sold by the selling shareholders. The principal purposes of this offering are to facilitate an orderly distribution of shares for the selling shareholders and to increase Proto Labs’ public float. Proto Labs intends to use the proceeds that it receives from the offering to pay the expenses that it incurs in connection with the offering and for working capital and general corporate purposes. As part of the offering, Proto Labs, all selling shareholders, as well as all of Proto Labs’ executive officers and directors, have entered into lock-up agreements for a period of 90 days following the offering. Morgan Stanley & Co. LLC and Piper Jaffray & Co. are acting as joint book-running managers for the offering. William Blair & Company, L.L.C., Needham & Company, LLC, Craig-Hallum Capital Group LLC and Dougherty & Company LLC are acting as co-managers for the offering. A registration statement relating to these securities was declared effective by the Securities and Exchange Commission on November 15, 2012. This offering will be made only by means of a prospectus. A copy of the final prospectus, when available, may be obtained from the offices of Morgan Stanley & Co. LLC, Attention: Prospectus Department, 180 Varick Street, 2 nd Floor, New York, New York 10014, or by email at firstname.lastname@example.org; or Piper Jaffray & Co., Attention: Prospectus Department, at 800 Nicollet Mall, J12S03, Minneapolis, MN 55402, or by email at email@example.com This press release shall not constitute an offer to sell or a solicitation of an offer to buy, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.