Feasibility Review & Industrial Design Concept – Premium Refillable Bookmark Pen (CODEX)

I am seeking an experienced industrial designer or product designer to evaluate the feasibility of a new consumer product concept called CODEX. CODEX is a premium refillable bookmark pen designed for readers. Key Features: * 6” overall length * 4.75” bookmark body * 1.25” exposed grip above book * Twist-to-deploy ballpoint pen * No cap * Uses replaceable D1 refill * Flexible spring-steel bookmark body * Soft-touch premium finish * Integrated page-stop shoulder I am NOT looking for full CAD development at this stage. I am looking for: 1. Feasibility assessment 2. Internal layout recommendation 3. D1 refill integration concept 4. Twist mechanism recommendation 5. Durability review 6. 2–3 refined concept sketches/renderings The primary question is: Can a premium bookmark remain approximately 1.5–2.0 mm thick while incorporating a D1 refill, twist mechanism, page-stop shoulder, and spring-steel core? Please provide: * Relevant product design experience * Examples of pens, stationery products, EDC products, or small mechanisms * Estimated timeline Successful completion may lead to a second project for CAD and prototype development. Initial budget $250 to $500.