Free BricsCAD Shape concept modelling tool & Free 2D Draftsight Cad Drawing Software both with .DWG file extension

Free Cad packages are fine, but a lot of time you are collaborating with others who are using the industry common tools and having to save files in a .DFX or other intermediate format ( Revit/ArchiCAD with IFC etc) always causes data loss and issues when transferring to another package, so having something that saves