Yellow Submarine Toy

The problem

Every consumer product that reaches mass market has solved a problem most engineers never think about: how do you make it for almost nothing, at millions of units, without hurting anyone? The brief was a simulated client engagement. Design a Happy Meal toy that is fun, low-cost, sustainable, safe for children, and fully producible by injection molding. Deliverables included a manufacturing plan, part cost at production scale, safety testing, a sustainability rationale, and a live pitch at the Duke Toy Fair.

What we built

A Beatles-inspired wind-up submarine for ages 5 to 8, for use in water. Two coil springs drive side-mounted paddle wheels, with a rotatable periscope and molded hull detail. The single-body form factor was chosen to eliminate loose parts and the choking hazard that comes with them.

I was design lead on a three-person team and owned the hull, overall assembly integration, and co-developed the paddle wheel mechanism.

• Hull. Single-piece sealed body for buoyancy and strength, molded windows, filleted edges throughout, tolerance-fit closure against water ingress, wall thickness and draft angles set for molding
• Paddle wheels. Internally structured spokes sized to pass choking hazard testing, geometry tuned for thrust without sharp blades
• Assembly integration. Coordinated interface dimensions at ±0.003 in, produced the exploded view and the tolerance stack-up
• Materials. rPET and PBAT to meet the sustainability requirement
• Safety. All separable parts validated against the standard choking hazard cylinder (1.25 in internal diameter, slanted base 1 to 2.25 in deep)

Cost model

Production cost was estimated with a plastic part cost estimator, modeling 6-ton press equipment at 99.999% yield.

Projected run: about 2 million parts a year across 4 injection molding machines, roughly $798,000 in annual production cost at full scale.

The Toy Fair

We presented at the Duke Toy Fair, a live public tradeshow. The 3D-printed prototype worked and demonstrated the spring-driven paddle mechanism in water.