I've recently started looking for good, no cost CAD software to work on my solids designs. I wanted to find something that's anyone can get and use continuously, so no expensive packages or time limited demos.
My original hunt lead me to open source. From there, I ran into the following software. I'm still just touching on these right now, so I might be missing the big picture.
BRL-CAD is an open source implementation of the Army Ballistics Research Laboratory solid modeling package. They use it to do simulations of various combat scenarios. Its results look pretty, but the Windows package I looked at shows that this is going to be a command line driven uphill battle. It's essentially a collection of very powerful software bits that can read and work on the same data set.
Another CAD package, although this is not based on a US DoD project. Seems similar in capability to BRL-CAD, and also may be command line based. What got me interested in looking at this one is that it has close ties to various finite element analysis software packages.
Ah, an old open source 3D modelling standby. While you can do solid CAD style modelling with it, and it has a much better UI for diving into it than the prior two, it doesn't appear to do solid modeling, which may cause issues if you want to post-process the component.
Now, there's also a few "freebie" packages I'm investigating. As they're based on commercial packages for Windows, they tend to be at least easier to dive into within a few minutes. I'll have to see how everything stacks up in the long run.
Solidedge 2D V19
Basically the 2D component of SolidEdge, this is a really REALLY nice free 2D CAD package. It's not AutoCAD, but it reminds me of the fast and simple CAD package I learned on back in high school. It's also nice that it can open and edit all AutoCAD files, and can export into AutoCAD and MicroStation formats, so it's not locking you into its format.
Alibre Design Express
I'm just going through the initial tutorial for this one. If it's up there in capability with SolidWorks and SolidEdge, this one's a keeper. They've removed the ability to work with sheet metal forms and the ability to generate bill of materials (these are usually addons in other programs anyway). However, it looks like it's all there, I'll give it a try and I'll have to follow up on this at some point in the future.