Careers

At 3Si, our mission is to make your world, safer. As a global leader in innovative security technology, we help businesses and law enforcement prevent and respond to crime through field-proven solutions and trusted partnerships. With over 100+ years of combined experience through our merged companies, our expertise drives measurable impact in communities worldwide.

We specialize in GPS tracking, video surveillance, and integrated response technologies that deter theft and accelerate criminal apprehension. Designed for retail, financial institutions, law enforcement, and more, our solutions combine cutting-edge tools with unmatched response capabilities. Through our exclusive DirectToDispatch™ technology, verified crime alerts are sent directly to law enforcement dispatch centers in real time—bypassing traditional third-party monitoring delays—to enable rapid, precise response when it matters most.

At 3Si, meaningful work makes a difference. We’re a purpose-driven team that values innovation, trust, and collaboration. From engineering to sales and support, every role contributes to our mission to protect communities and make the world safer. We offer a hybrid, flexible work culture, competitive benefits, and the chance to grow alongside a team of passionate, dedicated professionals.

Join us—and be part of something that matters. We are looking for a detail-oriented, Mechanical Engineer to join our engineering team in Jefferson City, MO. This position is an opportunity to apply your engineering knowledge, build hands-on design experience, and contribute to the development of production-ready components and assemblies.

 Working alongside experienced engineers and cross-functional teams, you will support products from concept through production, with an emphasis on designing parts for injection molding and high-volume manufacturing. You will develop your knowledge of Design for Manufacturability (DFM), tooling considerations, and material selection while helping optimize designs for cost, quality, and manufacturability.

Primary Responsibilities

• Design and develop mechanical components and assemblies to meet project specifications and applicable industry standards.
• Collaborate with engineers, project managers, manufacturing and quality personnel, and tooling vendors to support product development.
• Utilize CAD software for design creation and modification, ensuring accuracy and adherence to project timelines.
• Prepare and update technical drawings, specifications, and related documentation for manufacturing and assembly.
• Support prototype development, testing, and analysis; document results and help identify opportunities for design improvements.
• Participate in design reviews and assist with resolving design and manufacturing issues throughout the product lifecycle.
• Learn and apply DFM principles, including material selection and tooling considerations for injection molding and/or die casting.
• Continue developing technical skills and knowledge of mechanical design, materials, and manufacturing processes.

Knowledge, Skills, and Abilities 

• Foundational understanding of mechanical engineering principles, materials, and manufacturing processes.
• Interest in learning about injection molding and/or die casting, including part design and tooling considerations.
• Strong attention to detail and a practical approach to problem-solving.
• Ability to organize tasks, manage competing priorities, and communicate progress with guidance from the team.
• Effective communication and teamwork skills, with a willingness to ask questions, seek feedback, and learn from others.

Qualifications

• Bachelor’s degree in Mechanical Engineering or a related field required.
• 0–3 years of relevant mechanical engineering or product design experience.
• Familiarity with CAD software through coursework, academic projects, internships, or professional experience; SolidWorks experience preferred.
• Exposure to injection molding, die casting, or DFM through coursework, projects, or work experience is a plus

Additional Comments

• Position is based in Jefferson City, MO.
• In-Person requirement M-F, 8:00 am to 4:30 pm CT.
• Less than 5% of travel.