Principal AI Engineer / ML Engineer

About Backflip

Backflip (Backflip.ai) is a generative AI startup revolutionizing how engineers and designers create for the physical world. Founded by the team behind Markforged, we're building AI-first tools that make 3D CAD as intuitive and fast as sketching on paper. Backed by Andreessen Horowitz and NEA, we’ve raised a $30M Series A and built a deeply technical, mission-driven team of 15. Our goal : empower one engineer to work at the speed of a hundred.

The Role

We’re hiring a Principal AI / ML Engineer —a top-tier individual contributor who sets the technical bar, shapes our AI direction , and tech-leads critical projects without direct reports. You’ll architect, prototype, and productionize multimodal generative systems that power our CAD engine.

What You’ll Do

Co-define the technical strategy for generative modeling with the Head of AI; influence roadmap through hands-on prototypes and data-driven recommendations.

Architect end-to-end systems across LLMs, diffusion, and retrieval; design interfaces between perception, reasoning, and CAD-specific geometry modules.

Tech-lead projects : drive design reviews, create implementation plans, de-risk research, and ensure high-quality, shippable outcomes.

Own the model lifecycle : dataset curation, training / eval, optimization, low-latency inference , monitoring, and continuous improvement.

Raise the bar : establish coding standards, reproducible experimentation, benchmarking, and model / infra observability.

Mentor and unblock engineers and researchers (guidance, pairing, design reviews) while remaining an IC with no direct reports .

Collaborate with product / design to translate ambiguous user needs into concrete AI capabilities; instrument and iterate quickly.

What We’re Looking For

3-7+ years in deep learning / generative AI with a record of shipping complex systems.

Expert in multimodal and generative models (transformers, diffusion, autoregressive); strong Python + PyTorch .

Evidence of technical leadership as an IC : you’ve set standards, led cross-functional efforts, and made architectural decisions that lasted.

Fluency from research to production : data strategy, training, tooling, serving, and performance engineering.

Bonus

Experience with CAD , 3D geometry, graphics, differentiable programming, or AI for the physical world.

Why Backflip

Repeat founders in 3D printing / CAD with a prior $2.1B exit ; backed by a16z and NEA . In-person in SF with a tight-knit, world-class team building the future of 3D design.

Flexible PTO and competitive compensation

3 days a week in our San Francisco office, 2 days remote with the option to come in more often

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