> Investor Presentation June 2016

> Investor Presentation June 2016

These slides and accompanying oral presentation contain forward-looking statements. These statements relate to future events or to future financial performance and involve known and unknown risks, uncertainties, and other factors that may cause our actual results, levels of activity, performance, or achievements to be materially different from any future results, levels of activity, performance, or achievements expressed or implied by these forward-looking statements. In some cases, you can identify forward-looking statements by the use of words such as may, could, expect, intend, plan, seek, anticipate, believe, estimate, predict, potential, or continue or the negative of these terms or other comparable terminology. You should not place undue reliance on forward-looking statements because they involve known and unknown risks, uncertainties and other factors that are, in some cases, beyond our control and that could materially affect actual results, levels of activity, performance, or achievements. Other factors that could materially affect actual results, levels of activity, performance or achievements can be found in Proto Labs SEC filings, including the Form 10-K for the year ended December 31, 2015 and the quarterly Form 10-Q filings. If any of these risks or uncertainties materialize, or if our underlying assumptions prove to be incorrect, actual results may vary significantly from what we projected. Any forward-looking statement you see or hear during this presentation reflects our current views with respect to future events and is subject to these and other risks, uncertainties, and assumptions relating to our operations, results of operations, growth strategy, and liquidity. We assume no obligation to publicly update or revise these forward-looking statements for any reason, whether as a result of new information, future events, or otherwise.

> Who We Are

> About Proto Labs Proto Labs is a digital manufacturer that helps companies large and small improve product development, reduce risk and accelerate product launch. World s fastest on-demand manufacturer of custom prototypes and low-volume production parts. Unprecedented speed-to-market value for product developers and engineers worldwide. Capability to ship parts as soon as the same day they are ordered. ecommerce-driven digital manufacturing model. Proprietary software automation reduces development cycle and design risks driving significant savings for companies. Technology-agnostic with three distinct rapid manufacturing services: Injection molding CNC machining 3D printing 4

> A Brief History

> A Reputation for Financial Growth A Strong Foundation 1999 2006 Rapid Expansion 2007 2011 A Public Introduction 2012 2013 Eyeing the Future 2014 & Beyond 1999 Humble beginnings: ProtoMold founded 2005 European expansion: Manufacturing plant opened in the UK 2007 New service: Firstcut CNC Machining launched 2009 Rebranded: Protomold + Firstcut = Proto Labs Japan expansion: Manufacturing plant opened 2010 Revenue builds: >$50 million 2012 Revenue doubles: >$100 million, EPS of $0.98 per share IPO in February at $16 / share valuing the company at $370 million New injection molding facility opened in MN 2014 Revenue doubles, again: >$200 million, EPS of $1.60 per share Vicki Holt named CEO FineLine Prototyping acquired adding 3D printing service New MN facility opened LSR and lathe manufacturing processes launched 2015 Growth continues: Germany-based Alphaform AG acquired

> Where We Are Today

> 8 Manufacturing Locations on 3 Continents

> Digital Manufacturing Services >> 3D PRINTING >> CNC MACHINING >> INJECTION MOLDING Stereolithography Selective Laser Sintering Direct Metal Laser Sintering Milling Turning Plastic Injection Molding Liquid Silicone Rubber Industrial 3D printing works best for rapid prototyping, complex designs, multipart assemblies and even functional, end-use parts. Stereolithography (SL), selective laser sintering (SLS) and direct metal laser sintering (DMLS) are offered. Volume: 1 to 50+ parts Speed: Shipped in 1 to 7 days Cost: Starting at $95 Our machining capabilities include both milling and turning with live tooling. Quick-turn machining is ideal for functional prototypes, non-orthogonal parts and end-use components in small quantities. Volume: 1 to 200+ parts Speed: Shipped in 1 to 3 days Cost: Starting at $65 Rapid injection molding produces thermoplastic and liquid silicone rubber parts. It s ideal for engineering-grade prototypes, bridge tooling and lowvolume production parts. Volume: 25 to 10,000+ parts Speed: Shipped in 1 to 15 days Cost: Starting at $1,495

> 2015 Revenue by Service and Geography REVENUE BY SERVICE REVENUE BY GEOGRAPHY 3D Printing 9.5% Other 0.5% Japan 3.3% Europe 18.0% CNC Machining 28.2% Injection Molding 61.9% United States 78.8%

> Industries Served 12

> Follow the Numbers (2015) Unmatched on-demand, custom manufacturing scale. UNIQUE PRODUCT DEVELOPERS SERVED: 27,235 in 2015 PARTS MOLDED: 2.9 million each month PARTS 3D PRINTED: 45,000 each month MACHINES MANUFACTURING PARTS: 750+ ONLINE QUOTES GENERATED: 2 million PARTS MACHINED: 40,000 each month COMPUTING POWER: 1 trillion floating point operations per second 13 BASED ON 2015 GLOBAL STATISTICS.

> Speed to Market We help move products to market faster than traditional manufacturers. 12 WEEKS Automating front-end of injection molding can save up to 12 weeks

> Customer Story: Lockheed Martin

> Maintaining Consistent Growth

> Growth Story RECORD SALES Compound annual growth rate of 28% since 2012 2015 FINANCIAL DATA Revenue up 26% to $264 million Diluted EPS up $.23 to $1.97 Gross margin: 58.6% Operating profit: 25.4% GROWTH Diverse, growing customer base TECHNOLOGY Proprietary technology creates high barrier to entry ADDRESSABLE MARKET LEADERSHIP TEAM Strong organic growth with large total addressable market New executive team focused on continued growth 17

> Growth Strategies Significant opportunity to capitalize on the current Total Addressable Market - estimated at $7 to $8 billion 2 Broaden Part Envelope Larger sizes Increased complexity New materials 1 Expand Customer Base Acquire new customers Increase sales within existing customers Expand geographically 3 Launch New Manufacturing Processes 18

> Strong and Steady Growth >> This is a key metric in measuring the growth of our business as it captures both new customers and growth in existing accounts.

> Competitive Advantage

> Digital Differentiation >> ProtoQuote >> ProtoFlow Analysis Proprietary Quoting Applications Proprietary CAD Applications >> Manufacturability Analysis Web-enabled Sales & Support System Proprietary CAM Applications Online Marketing Resources Proprietary Manufacturing Applications >> Automated Toolpath Generation >> Process Planning, Control & Monitoring

> Massive Manufacturing Scale

> Automation CAD analysis + Design feedback + Ordering + Production Custom parts as fast as same day

> Agility Between Manufacturing Processes

> Research & Development Investment New Materials New Capabilities Titanium (machined) Nylon (3D printing) Software Turning 5-axis milling New Processes ecommerce platform CAD analysis Manufacturing software New Services 25 LSR molding Overmolding 3D printing

SMALL SHOPS PRODUCTION FACILITIES Small Shops In-house or machine shop operations are labor intensive and focused on complex parts. SPEED COST QUALITY SCALE RANGE OF SERVICES ACCESSIBILITY Production Facilities Large-scale manufacturing operations are focused on high-volumes, low-margins. >> Proto Labs is a highly scalable company optimized for low-volumes and high-margins.

> Financial Overview

> Steady Growth Annual Revenue (in $ millions) $300.0 $250.0 $200.0 $150.0 $100.0 $50.0 $- 2010 2011 2012 2013 2014 2015 28

> Consistent Profitability Adjusted Net Income* (in $ 000 s) 29 * Net income plus after-tax stock based compensation and intangible asset amortization.

> Long Term Financial Model Long Term Target GAAP Non GAAP Adjustments Long Term Target Adjusted Revenue Growth 20 25% 20 25% GAAP Operating 200 to 250 basis 26 29% 28 30% Income points Gross Margin 58 62% 58 62% Marketing & Sales 13 15% 50 bp 12.5 14.5% Research & Development 6 8% 50 bp 5.5 7.5% General & Administrative 30 9 10% 100 to 150 basis points 8 9%

> Cash Generation Operating Cash Flow In $ 000 s $60,000 $50,000 $40,000 $30,000 $20,000 $10,000 $- 2011 2012 2013 2014 2015 Equipment Investment Facility Investments Free Cash Flow 31 Investments in equipment and facilities predominantly support future growth Annual operating cash flow is sufficient to fund growth capital and increase cash position

> Strong Balance Sheet (in millions) 2012 2013 2014 2015 March 31, 2016 Cash & Investments $98.9 $143.4 $128.4 $145.6 $157.2 Accounts Receivable $15.8 $18.3 $24.2 $36.1 $36.2 Inventories $4.6 $5.2 $6.2 $9.8 $9.9 PP&E $45.3 $56.1 $91.6 $125.4 $130.3 Short & LT Debt $0.6 $0.4 $0.1 $0.0 $0.0 32

> Summary Unmatched financial performance Strong revenue growth, even in challenging economy Very strong margins Consistent revenue and earnings growth Leader in emerging digital manufacturing market Significant perpetual growth opportunity Proprietary technology: strong barrier to entry 33