Cool Idea! 

• Define the primary goal of your robotic hand. Is it for educational purposes, as an assistive device, or a creative exploration of robotics?
• Consider the end-users: Are they students, hobbyists, or individuals who could benefit from an extra functional hand?
• How will it work in reality? Is it powered by some electronics? Does it include any sensors?

Prototyping

• Instead, cut out different parts (like fingers and joints) separately so the hand can move more naturally. This way, the structure isn’t flat, and you can achieve more realistic bending and articulation.
• String or Fishing Line: To simulate tendons, use string or fishing line. Running the line through each joint allows for finger movement when pulled.

Inspiration

https://sek.nuvustudio.com/projects/114402-07-low-fidelity-prototyping-wearable-cardboard-mock-ups/tabs/134119-example-for-hand-mechanisms