It's good easy to learn to use for MEP Drawings Brics CAD can use Cad & BIM extension file DWG # Philemon _Dubai
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
SketchUp - 3D for Everyone
FreeCAD - An open-source parametric 3D modeler
Sculptris - Sculptris: Enter a world of digital art without barriers.
DraftSight - Discover Dassault Systèmes®' DRAFTSIGHT™ Professional CAD software that lets you create, edit, view and markup any kind of 2D drawing. Learn more here.