Exhibit 3.1

AMENDMENT NO. 1

TO THE AMENDED AND RESTATED BYLAWS OF

THE EXONE COMPANY

The Amended and Restated Bylaws of The ExOne Company are hereby amended, effective as of August 19, 2013, to add the following new Article XIV:

Article XIV.

Exclusive Forum

Unless the Corporation consents in writing to the selection of an alternative forum, the sole and exclusive forum for (i) any derivative action or proceeding brought on behalf of the Corporation, (ii) any action asserting a claim of breach of a fiduciary duty owed by any director or officer or other employee of the Corporation to the Corporation or the Corporation’s stockholders, (iii) any action asserting a claim against the Corporation or any director or officer or other employee of the Corporation arising pursuant to any provision of the Delaware General Corporation Law or the Corporation’s Certificate of Incorporation or Bylaws (as either may be amended from time to time), or (iv) any action asserting a claim against the Corporation or any director or officer or other employee of the Corporation governed by the internal affairs doctrine shall be a state court located within the State of Delaware (or, if no state court located within the State of Delaware has jurisdiction, the federal district court for the District of Delaware).