Cost-Optimized Integrated PCB Redesign

I already have the circuit working on a hand-wired board that combines an Arduino Nano, ULN2003-driven 28BYJ-48 stepper, RTC, I²C OLED, and two rotary encoders with push buttons. What I now need is a polished PCB that can roll straight into a manufacturing order while driving the overall unit cost down.

Scope of work
• Replace the plug-in modules with their discrete components so the board is smaller and cheaper, yet the pinout remains firmware-compatible with my existing Cyclick code.
• Add a convenient programming interface—ISP, USB-C, or similar—so I can flash new firmware without pulling the MCU.
• Provide robust, keyed headers (or another clean solution you prefer) for the external OLED and the two encoders.
• Supply all production files: schematic, PCB layout, Gerbers, drill files, pick-and-place, and a concise BOM with part numbers and estimated pricing.

I am prioritising cost reduction, so thoughtful component selection and compact routing will be valued. Show me examples of past PCB designs where you replaced modules with discrete parts or otherwise cut cost; that experience will weigh heavily in my decision.

I’m comfortable reviewing designs in KiCad, Altium, or Eagle—use whichever suits you. Let’s get this into the fab queue quickly and start saving money on every board we build.