For 2D, LibreCAD is quite serviceable (and very AutoCAD-like). For 3D there's FreeCAD, but, IMO, while it is nominally quite capable, the UI is so obtuse and i

For 2D, LibreCAD is quite serviceable (and very AutoCAD-like). For 3D there's FreeCAD, but, IMO, while it is nominally quite capable, the UI is so obtuse and inconsistent that after a few hours with it, you'll just pay whatever Autodesk is asking you to pay. That's not to say F360 is great, but FreeCAD is unfortunately much worse. I really wanted to like it, since I don't like my work to be tied to proprietary software, but after digging through it for a week I was back to F360.