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