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 CTO and 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.