Open source AutoCAD
 

https://opensource.com/alternatives/autocad

Has anyone tried this sort of thing? The software on this stuff is not cheap, I don't need it that badly, but it could be handy.

I briefly downloaded and ran Google's "sketchup" a year or two ago.
(background - 10 years ago I went through Mech. Eng. Technology school and was not bad at CAD with Solid Edge and Solidworks (student editions :)

Sketchup seemed good for a non-experienced CAD person, it snapped everywhere and as someone with 'traditional' CAD training that was annoying. I could have learned to adapt to its nuance, but I never really had a project to work on so my interest faded.
I could have made 2D drawings on it though. Not sure if it handled title blocks (etc.) though, never tried.

-JcG

2D or 3D?

For 2D I used Draft Sight. Pretty much an Autocad knockoff. Will save files in several formats. Made by Dassault, the producers of SolidWorks.

http://www.3ds.com/products-services/draftsight-cad-software/free-download/

Never found a good 3D application. They all had some annoying quirk which made them incompatible with most accepted drawing programs.

Thanks for the advice. I'm only interested in 2-D at this point. Would be great to know 3-D, I'm guessing one needs to buy quality software and go through a steep learning curve to get it down

You might look into this:

Free Student Software Downloads | Autodesk Education Community

It is also possible to get older editions of ACAD by way of Ebay and/or used software stores. The older stuff is pretty inexpensive and for messing with it or formal study, even a 5-10 year old or older edition will be fine.

ACAD has largely gone to a subscription model and regular users tend to use the latest editions and toss earlier ones.

For 3D CAD on a budget (or free for some users), I've heard some really good things about Autodesk Fusion 360.

I think it's interesting that they are offering some fairly serious software for free, for real, and not just to students:

If one has to move beyond "free", one can go subscription for $40/month or $300/year.

(Autodesk Inventor user here; almost no personal experience at this point with Fusion 360.)

The key thing for any of the free cad software packages you consider is the format in which they save their files. If they only save their drawings in their own format they are useless except as a learning tool.

Nothing wrong with that but if you intend to actually use your work then you need to be aware of this.