Dificult to find a CAD software that’s free to use

From time to time I make an effort to know what’s out there regarding simulation and CAD applications.

Free software are allways evolving and it is good practice from time to time to see what’s available out there.
This time around my quest was for a good (suficient) CAD editor and STP viewer. I found a list of many packages in the link bellow however after reviewing each of the links I got a little disapointed with what I learned.
From start major packages were disqualified: Solidworks, Catia, Siemens NX, Creo, Autodesk Inventor, Spaceclaim, Solid Edge and AutoCAD. All major software packages that I could remember off.
On the list I noticed a mixture of DWG and 2D CAD files with 3D models files like .STEP, .IGES. The 2D versions were also disqualified leaving only a few candidates.

http://listoffreeware.com/list-of-best-free-cad-viewer-software/

The list shows many projects and might have something useful, though not for my purposes.

But to be honest I could not use effectivelly any of the offereings.

What I really like to use and edit CAD files:

• Free CAD (Any use)

• SketchUp (Personal use)

• Design Spark Mechanical (Any use) My preference

Unfortunatelly aside from Free CAD I could not find any good software for a mac system which is free. I wish DS Mechanical would come in Mac version.
The good thing here is that DS Mechanical is Spaceclaim but more simplified. It’s Enough to work with and produces great results. So my recomendation is to use Desgin Spark Mechanical.

• Easy to model and learn (Push and Pull interface)

• Good rendering

• Easy 2D sketch

Design Spark Mechanical
Design Spark Mechanical