Small-Scale Mechanical Prototype Design

I need a mechanical engineer that's a professional with creating a mechanical prototype which can be 3D-printed. the prototype should simulate the physics of my idea. Note that the product idea requires hydraulics, fluids and automotive engineering.

due to my limited skills in demonstration, I would need also to have a call with the candidate to make sure that what I'm trying to achieve is clear and I want also to learn more on how I can make my idea usable in real life.