Principal Mechanical Systems Engineer

Fabri is seeking a Principal Mechanical Systems Engineer to architect, design, and deliver the in-house equipment that defines our manufacturing capabilities. This is a foundational role: you will work directly with the executive team to shape Fabri’s technical roadmap, report to the CEO, and own mechanical systems that span every step of our process.

Your work will directly determine Fabri’s scalability, cost and throughput curves, automation strategy, and the architecture of future facilities. You will make and execute on critical build vs. buy decisions, develop first-of-their-kind equipment on aggressive timelines, and create hardware that radically expands what our process engineering teams can do. This role is expected to grow into technical leadership and the buildout of Fabri’s in-house equipment and mechanical engineering organization.

We are looking for someone who thrives in high-ownership startup environments, is comfortable with ambiguity, and can move seamlessly between first-principles analysis, detailed machine design, and hands‑on execution on the shop floor. You will “build the machines that build the machines” for some of the US’ most critical industries.

We are an early‑stage investment casting startup building a fully integrated digital foundry. Our mission is to deliver precision metal castings with unparalleled speed and cost‑effectiveness. By leveraging our exclusive high‑throughput additive manufacturing process and AI‑driven design software, we can deliver castings in days, saving our customers critical time and money. We are well capitalized and backed by top‑tier investors and major customers, with significant funding raised in the past year.

We’ve shipped our first customer parts and have generated significant commercial excitement in both the aerospace and industrial sectors.

Fabri is located in Boston Metrowest. During this startup phase and for the foreseeable future, all employees will be on‑site and closely involved with building and operating the end‑to‑end process.

Fabri is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. We foster an environment where safety and commitment to quality are central in everything we do.

As Principal Mechanical Systems Engineer, you will own the design, development, and deployment of Fabri’s core manufacturing equipment. You will operate bidirectionally with process engineering: translating process requirements into hardware, and using mechanical system constraints and opportunities to drive new process capabilities.

• Define and communicate Fabri’s equipment and mechanical systems roadmap
• Architect systems end‑to‑end, from concept through commissioning and production
• Ensure that equipment choices scale economically in throughput, yield, automation, and facility footprint
• Act as a systems engineer across tightly coupled mechanical, thermal, fluid, controls, materials, and process domains
• Design, build, assemble, and troubleshoot critical hardware on tight timelines

This is not a role focused on incremental optimization. You will be expected to question every requirement, clearly define the underlying problem, explore the full solution space using first‑principles physics, and deliver practical solutions fast.

• Lead the architecture and design of custom, first‑of‑kind manufacturing equipment across all process steps
• Make and execute build vs. buy decisions based on physics, economics, scalability, and long‑term roadmap impact
• Work closely with process engineers to translate process needs into mechanical systems and use mechanical design to unlock new process regimes
• Apply a systems‑engineering mindset to track linked requirements, interfaces, and downstream consequences of design decisions
• Drive rapid iteration: prototype, test, fail, learn, and deploy on short timelines
• Define equipment architectures that support automation, reliability, maintainability, and future facility scale‑out
• Communicate complex, multidisciplinary technical decisions clearly to engineers and executive leadership
• Help…