MAPLE PLAIN, Minn.--(BUSINESS WIRE)--Proto Labs, Inc. (NYSE: PRLB), a leading online and technology-enabled, quick-turn, on-demand manufacturer, today announced financial results for the first quarter ended March 31, 2015. Highlights include: Revenue for the first quarter of 2015 increased to a record $58.5 million, 27 percent above revenue of $46.1 million in the first quarter of 2014, and an increase of 31 percent versus the prior year in constant currencies. Revenue from additive services (3