Electrical Engineer — 2 PCBs for a screen-free kids' toy (NFC, e-paper, magnetic chain)

Lekko is a screen-free learning toy for children ages 4–8. A hub reads a challenge from a tapped NFC card, speaks it aloud, and shows it on a pixel- style LED face. Children answer by snapping small illuminated blocks together magnetically — the system detects which blocks are connected and in what order, and lights each one green, amber or red. A working three-block prototype exists today and runs the complete interaction. I wrote the firmware myself. I have also designed, manufactured and shipped a small-batch electronic product before boards, firmware, enclosures and fulfillment for a run of about 160 units. I need two production-intent PCBs designed for a small fab/assembly run (JLCPCB-class) to build demo sets. WHAT YOU'D BE DESIGNING Board 1 — Hub. MCU (ESP32-class or your recommendation), NFC reader, audio from soldered SPI flash + codec/amp + speaker, a custom 16×16 addressable LED board behind a diffuser, LiPo + USB-C charging with power-path, one multifunction button. Roughly 62 × 62 mm, likely a two-board stack. Board 2 — Block. Low-cost MCU, one RGB LED, a small e-paper display, and contact interfaces on two opposing faces. Ideally no battery — powered entirely through the chain. This board is built 7× per set, so minimum BOM cost is a first-order concern. THE HARD PARTS, STATED UP FRONT 1. The hub's front face is both the LED display AND the NFC tap zone. An antenna with a display in its aperture and a populated board behind it is a hostile environment. I consider this the highest-risk item and want your view on ferrite shielding, loop area, keep-outs and tuning. 2. Can the blocks be batteryless? E-paper holds its image at zero power, so in principle a block draws from the chain to update and is inert in between. I need the update energy, whether the chain can deliver it to seven blocks without a brownout, and the voltage drop across the chain. This question decides the product. 3. Magnetic pogo contacts, mirrored. The two mating halves are mirror images, and reverse mating must be physically impossible — I destroyed a board early on by shorting power to ground. I want a researched recommendation on contact technology, plating, magnet spec, keying and cycle life, with at least two options compared. ENGAGEMENT Phase 1 (paid, ~1–2 weeks): answer a set of written open questions with your recommended architecture and a rough BOM. We align before layout begins. Please quote this separately. Phase 2: schematics and layouts for both boards, through fab-ready files, plus at least one revision round after prototype boards are tested. Firmware is NOT in scope — I write it. Boards must expose programming interfaces and test points. An industrial designer joins after your layouts stabilize; one short paid handoff call with them is included, as the contact-face geometry is jointly owned. Deliverables: schematics (PDF + native source), layouts (native + Gerbers), full BOM with sourcing, board outline STEP/DXF for the mechanical designer, and a short design-notes document. All work product is the exclusive property of Lekko LLC (work-for-hire, in the written agreement). A detailed 11-page brief with full specifications and 16 open questions is available under NDA. IN YOUR PROPOSAL, PLEASE INCLUDE - 1–2 relevant portfolio examples — small consumer, toy or wearable hardware preferred - Your NFC antenna and battery-design experience specifically - Your toolchain (Altium / KiCad / Eagle) - JLCPCB-class fab and assembly experience - Your proposed structure — fixed price per phase or hourly — and timeline - Anything in the above you'd approach differently. I have built a working prototype, not a product. If something here is naive, saying so is exactly what I'm hiring for.