Embedded Systems / PCB Engineer for Handheld Children’s Electronic Game (36-Button Device)

I am developing a children’s handheld electronic game device with illuminated buttons.
I currently have a working Arduino-based prototype using off-the-shelf components, including a 4×4 illuminated button grid. The prototype validates the core concept, but it is not suitable for production.
The goal of this project is to transition the device to a custom PCB-based design that is scalable, cost-effective, and suitable for manufacturing.
This project is patent pending. Full details will be shared only after an NDA is signed.

I am seeking an experienced embedded systems / PCB design engineer to:
Replace the Arduino-based prototype with a custom PCB
Go from 4x4 (16 buttons) to 36-button (6×6) illuminated button grid
Add buzzer and timer
Select appropriate components with manufacturability and cost in mind
Prepare the design for small-batch production

This is a self-contained handheld device (no wireless, display, or mobile app).


After NDA execution, I will provide:
Existing Arduino code
Photos/videos of the current prototype
Functional description of device behavior
Your responsibilities will include:
System architecture and component selection
Schematic design

Job will complete:
PCB schematics
PCB layout files (manufacturing-ready)
Bill of Materials (BOM)
Firmware source code
Gerber files and pick-and-place files
Basic documentation for fabrication and assembly

This will be a fixed-price project with milestone-based payments (which we can discuss upon employment).

Requirements
Experience with embedded systems and custom PCB design
Experience converting Arduino prototypes to production boards
Familiarity with button matrices, LED matrices, or similar input/output designs
Ability to design with cost, reliability, and manufacturability in mind


Budget: Flexible / market rate

Timeline: Flexible, with clear milestones preferred

To Apply, Please Include
Examples of similar embedded or PCB projects you’ve completed
Tools you use for schematic and PCB layout (e.g., KiCad, Altium, Eagle)
Your experience designing products intended for manufacturing
Your proposed milestone breakdown