Prototype Mechanical Part CAD Design

I need a precise 3-D model of a mechanical part created in FreeCAD for an upcoming prototype. I will share the dimensions, functional requirements, and any reference sketches once we start; what matters most is that the resulting geometry is accurate enough for a first physical build and later refinement.

Because the part is only for prototyping at this stage, tolerances do not have to meet final mass-production standards, but clear callouts for critical fits are essential. If you prefer SolidWorks, AutoCAD, or Fusion 360, that’s fine—just be sure the final deliverables below are supplied so I can continue working in FreeCAD.

Deliverables
• Native FreeCAD (.FCStd) model with fully parametric history
• Neutral STEP or IGES file for cross-platform use
• Optional STL ready for 3-D printing to verify form and fit

Acceptance criteria
• All key dimensions reflect the provided spec within ±0.1 mm
• No feature errors when the file is opened in FreeCAD 0.21 or later
• Clean feature tree: sketches fully constrained and named logically

If this aligns with your skills, tell me briefly how you would tackle the modeling workflow and any similar prototype parts you have handled before.