FreeCAD Mechanical Prototype Assembly Design

I am starting a small prototype project and need several mechanical parts modelled from the ground up in FreeCAD, then brought together in a working assembly. You will be creating the geometry completely from scratch—there are no sketches, hand-drawn concepts, or prior CAD files to trace.

Here’s what I’m after:
• Individual part files (.FCStd) built with clean parametric feature trees so I can tweak dimensions later.
• A corresponding assembly file that shows how every component fits and moves (Assembly4 or A2plus—whichever you prefer).
• Exported STEP and STL for each part plus the full assembly so I can run quick 3D-print checks.
• Brief notes on key constraints, mating references, and any assumptions you had to make while designing.

Because this is strictly for prototyping, tolerances can follow typical FDM printing guidelines; I’ll confirm any critical fits during review. The job is complete once the models open error-free in the current stable release of FreeCAD and all parts mate without interference. If that sounds straightforward, let’s get started—I’m ready to iterate fast.