To echo LegitShady, FreeCAD is the only open source tool that even aspires to be anything like Fusion 360. Blender is essentially unusable for precise modeling

To echo LegitShady, FreeCAD is the only open source tool that even aspires to be anything like Fusion 360. Blender is essentially unusable for precise modeling since it doesn't have a constraints engine or a proper history. For example, you can't (easily) draw a 2D sketch of a rectangle with 5mm fillets, extrude that into a cuboid, drill a hole in it, then go back later and change the rectangle dimensions or the size of the fillets.