X0306 4 2018-05-16 0001443669 Proto Labs Inc PRLB 0001388884 Chand Sujeet 5540 PIONEER CREEK DRIVE MAPLE PLAIN MN 55359 1 Common Stock 2018-05-16 4 A 0 1064 0 A 4236 D The deferred stock units vest in full on May 16, 2019, but must be retained by the reporting person until the completion of the reporting person's service on the Board of Directors of Proto Labs, Inc. /s/ Samuel A. Rosenbaum, Attorney-in-Fact 2018-05-18