Prototype Engineer Intern Jobs in Boulder, CO (NOW HIRING)

About H3X Technologies

H3X is building America's advanced electric motor company, powering next-generation platforms in aerospace, defense, and marine. Our integrated motor drives deliver 12+ kW/kg, roughly 3x the power density of competing solutions. We're now scaling to megawatt-class systems, with customers working on everything from supersonic aircraft to turbine power generation for AI datacenters.

Our team brings together engineers and operators from aerospace, defense, and motorsports, with deep expertise in electric machines, power electronics, material science, and advanced manufacturing. We're a small, fast-moving team doing hard engineering that matters, and we're looking for people who want to do the best work of their careers alongside us.

About the role

H3X is looking to hire a mechanical design engineering intern to support the development across all aspects of the HPDM product line. This is not an ordinary internship. You will be given the full responsibility of a mechanical design engineer. The engineering team is intentionally small and operates at a very fast pace. A high degree of self-motivation and responsibility is required as you will be given significant freedom and will be directly responsible for your parts. We are focused on hiring Spring Interns, but will also have future Summer roles, and open to extended Co-Op periods.

What you will do:

• Requirements/Concept

  • Establish and document requirements

  • Conceptualize designs and product architectures that meet program requirements

  • Present in Concept Design Reviews

• Design and Analysis

  • Design parts and assemblies utilizing SolidWorks

  • Perform and document mechanical analyses, including hand calculations, FEA, CFD, etc. for structural, modal, thermal, and/or fluid aspects of products

  • Present in Preliminary and Critical Design Reviews

  • Generate engineering drawings per ASME and GD&T standards, perform tolerance stack-ups

• Prototype and Manufacturing

  • Compile complete Bills of Materials

  • Provide technical supply chain support for sourcing hardware

  • Work with technicians and manufacturing engineers to build initial prototypes

• Testing and Validation

  • Create a Design Validation Plan and Report (DVP&R) for new products and/or subsystems

  • Support testing execution and characterization of new designs

  • Interpret test results, identify root-cause of issues, and make design recommendations to meet the highest level of reliability and performance

• Integration

  • Integrate sub-systems into full systems

  • Support future production builds or complete system tests

• Other

  • Identify workplace hazards and implement safe processes

  • Maintain testing and production equipment where necessary

What we are looking for:

• Pursuing a Bachelor’s or Graduate Degree in Mechanical Engineering or similar

• GPA of 3.0 or higher

• Hands-on experience assembling mechanical systems

• SolidWorks proficient (or similar)

• Excellent written and verbal communication

• Exceptional understanding of fundamentals

• Action biased, results-driven mentality

• Willingness to learn quickly

Nice to Have Experience:

• Experience with manufacturing processes (machining, Metal AM, & composites)

• Experience with producing 2D part drawings & GD&T

• Experience with linear structural FEA

Compensation & Benefits

• Hourly Compensation Range: $23 - $37/hr based on school level & experience

• Flexible hours (deliverable-based goals)

• Relocation package

• Monthly company events

• Friday Team Lunches

Why H3X

Joining H3X means working on hard, meaningful problems with a skunkworks-style team that's laser-focused on building exceptional products. We're deeply vertically integrated and have a very tight design-build-test loop, which lets us move from concept to hardware at unmatched speed. We've gone from idea to shipping product in less than two months.

We're a small, highly skilled team where everyone carries real responsibility and shares an extreme ownership mentality. We stay focused on the critical path, keep bureaucracy to a minimum, and structure everything around delivering results. You'll learn and grow faster here than you would anywhere else.

You'll work alongside world-class engineers and builders who are pioneering electric motor technology at scale on some of the coolest programs in the industry, from supersonic aircraft to power generation for AI datacenters. If you want your contributions to be visible and your work to directly shape American reindustrialization, you'll feel at home here.

Our Values

Be Relentless Never give up, persevere until the job is done. Run toward problems, not away from them. Grit is key.

Gain insight through humility Approach every challenge with a learner’s mindset. Stay open to feedback, listen to others, and deepen your understanding through self-awareness. Put your ego aside and seek the truth in every discussion, especially when leading others.

Distill & Simplify Eliminate unjustified complexity and simplify wherever possible, whether in requirements, design, or execution. Use first principles thinking to distill every problem to its essence. Less is more.

Find your flow Engage fully and work with intention. Find the rhythm and deep focus that lets you do your best work. Discover your Ikigai - where your strengths, passions, and purpose meet and drive your personal fulfillment and team success. That is when the magic happens.

SEND (Solve, Evolve, Nail It, Deliver) Devise the best solution with the information at hand, test it, learn from it, and iterate quickly until you nail it. Nothing works perfectly the first time, but you should never hit the same issue twice. Stay laser-focused on solving customer problems and delivering solutions that create real value.

Equal Opportunity Employer

H3X is an equal opportunity-affirmative action employer and considers all qualified applicants for employment based on business needs, job requirements and individual qualifications, without regard to race, color, religion, sex, age, disability, sexual orientation, gender identity or expression, marital status, past or present military service or any other status protected by the laws or regulations in the locations where we operate.