If you design mechanical components and don’t have access to expensive commercial CAD software, FreeCAD may be a viable option for you. I’ve used it extensively for mechanical design over the last few years and with the 0.18 version it finally reaches the status of “usable without external tools” for me. The big changes for my workflow are the huge improvements to the 2D layout generation workbench (TechDraw) and significant improvements in both the updated geometry kernel (opencascade) and the unit handling in the constraints system.
New features can be viewed here: https://www.youtube.com/watch?v=85HlYXnaxbw. Although the released build has been out for a little while on their github, today is the first time I’ve seen it posted to their website which absent any other visible note I’m interpreting as an official release.