Hi Chance, You may have difficulty using Freecad in designing your prototypes for either Injection Moulding or Castings, as freecad does not have any opitions to add scale to the 3D models. You have to add contraction to both the Pattern and Corebox in the matal that you wish to make the casting or ...

Gi'Day Phil,
I read your post about help for designing 3D parts. I am not a CAD Draughtsman, I am a Patternmaker (now retired). I work with fully dimensioned 2D drawings, if you think that I might be able to assist you let me know.
Regards,
Robert Redd