Rapid Prototyping Engineer

About Tacit

We are an early-stage, deep tech startup based in San Francisco, developing innovative hardware that rethinks human-computer interaction. We are backed by General Catalyst, Khosla Ventures, and Greylock Partners, with a founding team from Stanford, BrainGate, Oculus, and Tesla. While we can’t reveal too much just yet, our team is tackling cutting-edge engineering challenges to bring revolutionary products to life.

About the role

We are looking for a Rapid Prototyping Engineer, an engineering generalist who sits at the intersection of R&D and hardware engineering. You'll work closely with our design, electrical, and sensing teams to rapidly design, build, and iterate on mechanical, electrical, and sensor prototypes for novel wearable devices — while also owning the assembly and test fixtures that make those prototypes buildable and repeatable.

This is a hands-on, builder-at-heart role for someone who thrives on ambiguity and enjoys turning a rough concept into a working, testable physical system. You'll be the person the hardware and research teams come to when something new needs to be designed, fixtured, built, and iterated on fast — and when successful, you'll turn those one-off builds into scalable, DFM-friendly processes that support our product ramp from NPI/NTI through production.

What you'll do

• Prototyping & Build

  • Rapidly design and fabricate mechanical, electrical, and sensor prototypes to support R&D experiments and engineering development for wearable and consumer-electronics form factors.

  • Build end-to-end prototype systems: from concept sketches through CAD, fabrication, wiring, sensor/RF component integration, and validation.

  • Develop quick-turn PCBs, flex circuits, wiring harnesses, and cable assemblies for prototype electronics.

  • Hands-on soldering and assembly of electrical and sensing circuit components, including delicate flex and fine-pitch work.

  • Evaluate and select sensors, actuators, and off-the-shelf components for integration into prototype systems.

• Fixtures & Tooling

  • Design, build, and iterate on assembly and test fixtures, jigs, and tooling from the ground up to support novel processes and ensure build quality and efficiency for complex devices and wearables.

  • Partner with design engineers to provide DFM/DFA feedback and drive design iterations before problems reach production.

  • Build fixtures that improve repeatability, cycle time, and debug visibility for both R&D builds and early manufacturing runs.

• Debug, Troubleshooting & Iteration

  • Perform hands-on assembly, troubleshooting, and debugging of electromechanical systems, isolating whether an issue is mechanical, electrical, or process-related.

  • Identify and address failure modes specific to wearable hardware (fit, comfort, cable management, contact forces, thermal effects, wear over repeated use).

  • Take initiative in driving design iterations, documenting findings, and proposing next steps with minimal supervision.

• Cross-Functional Collaboration

  • Collaborate with electrical, RF, mechanical, and firmware engineers to integrate hardware with control systems and test software.

  • Support NPI/NTI/R&D efforts, working closely with design and validation teams as products move from early prototype toward production intent.

  • Communicate build status, design risks, and recommendations clearly to both technical and non-specialist audiences.

  • Document designs, build procedures, and test results to support knowledge transfer and continuous design improvement.

Requirements

• Bachelor's degree in Mechanical, Electrical, Mechatronics Engineering, or a related field.

• 2+ years of experience in prototyping, R&D engineering, or hardware development, ideally in wearables, consumer electronics, robotics, or research lab environments.

• Required experience with NPI/NTI/R&D processes, taking hardware from early concept through pre-production.

• Proficiency in CAD software (Onshape, SolidWorks, or Fusion 360) with strong 3D modeling and drafting skills.

• Working knowledge of PCB design and electronics, and comfort with soldering electrical and RF circuit components, wiring, reading schematics, and integrating sensors.

• Hands-on ability to build and troubleshoot electromechanical systems.

• Hands-on expertise with rapid prototyping methods: 3D printing (FDM/SLA), laser cutting, CNC machining, sheet metal fabrication, and manual machining.

• Demonstrated experience designing and building assembly and test fixtures, jigs, and tooling from scratch.

• Excellent project management and cross-functional collaboration skills.

• Strong track record of troubleshooting, debugging, and iterating on designs independently.

• A builder at heart: someone who takes initiative, brings creativity and problem-solving to ambiguous challenges, and can work with minimal supervision.

• Excellent communication skills and comfort operating in a fast-paced, ambiguous environment where requirements evolve quickly.

Strong candidates may have

• Familiarity with wearable or consumer-electronics form factors and the constraints of designing for comfort, fit, and durability against the body.

• Experience with RF or antenna hardware integration and the fixturing challenges specific to RF test and assembly.

• Basic scripting ability (Python) for test automation, data collection, or hardware interfacing.

• Experience supporting builds across EVT, DVT, and PVT stages with contract manufacturers

Success in This Role Looks Like

• Research and design concepts are rapidly and reliably turned into working physical prototypes.

• Assembly and test fixtures enable consistent, repeatable builds across R&D and early production runs.

• DFM/DFA feedback delivered early prevents costly design iterations downstream.

• Cross-functional teams have a trusted go-to person for hands-on build, debug, and fixture needs.

• Prototype learnings and fixture designs translate smoothly into scalable production processes.

Benefits

• Competitive equity package

• Comprehensive medical, dental, and vision insurance

• Company size: 30-50 people

• Unlimited PTO

• Visa sponsorship

• 4% 401k matching