I was originally trained as a architectural and engineering design drafter and learned by hand and autoCAD so i wanted to know if there was a good free or cheap program like that for designing game buildings and items ?

Game buildings and items are typically modeled in programs like Blender, 3DSMAX on Maya, where the precision of the model and parametric editing are not as relevant as in true CAD programs.

That said, you can use programs like FreeCAD (or other CAD tools you may find) to create your base models, export them to a mesh modeling software (like Blender) for unwrapping and organic detail modeling, and finally exporting from there to the game engine. AutoCAD itself supports export formats ypu can import to mesh modelers.

I used to do drafting professionally a long time ago, and I too was frustated by Max and Blender for their disregard for precision modeling and parametrics. I have found peace with them later on after realizing that the purposes of CAD and mesh modeling are, while related, still quite different.

One does not usually need extreme precision for game asset geometry as long as some base level is met. In exchange for lost control, mesh modeling is usually quicker and easier as you tend to typically manipulate a greater number of primitives with fewer operations, as compared to CAD where you typically manipulate one primitive or parameter at a time.

I use SketchUp for this purpose  

Thank you for your suggestions I don't like the free version of Sketchup  but i'll try  FreeCAD to start  the buildings/object then finish in blender (still confused by blender but guess i gotta learn) anyway thanks for the help now i have to practice more to be able to make usable materials