When I retired a couple years back I was unable to bring home my AUTOCAD drawing program and of course couldn't afford to buy one.
I found this LibreOffice ver 3.9 (For FREE) which does a bang-up job for me. This has a LIBRARY you can add to which saves alot of time moving things around to suit your drawing. I also love the file save in PDF format which almost anyone can view.
This is a typical drawing I did with my ver 3.9 LibreOffice. There is a newer version now on the market for free... Using my ADOBE ACROBAT PRO 9.0 I can edit alot of different images and save their pictorial drawings in the LibreOffice Library to use to make all kinds of neat pictorial type drawings like shown here.
Roy Ken