HeeksCAD

Start with the free option...

HeeksCAD/CAM looks to be a fairly robust open-source CAD/CAM alternative, at least from the screenshots and feature list. Unfortunately, its git has turned into a ghost town, no commits in 2-3 years. But hey, maybe it just works and there's nothing to update?

Screenshot

Firstly, I'm not using Linux as my primary OS and while it may be possible to build this package for OSX, I'm not really looking to do so when I keep a Linux VirtualBox around for other things anyway.

But there's a problem right off the bat...

VirtualBox's OpenGL implementation for 64 bit Linux hosts is in various stages of broken, and this being a 3d application, it is going to require and build from your installed OpenGL libs.

Going by this comment it may be possible to get Ubuntu 14 going with the required package versions in order. Ubuntu 14 ships with Virtualbox 4.3.10 tools/versions. The standard install of Ubuntu 14 currently installs a 3.19 series kernel which the 4.3.10 Guest Additions package (required for 3d acceleration) will not build against. The Ubuntu 'mini' CD will by default install a 3.13 series kernel so that's the route to go here. Ubuntu 14 also appears to have the desired 10.1.0 mesa package versions.

So as of now...

And for the record I did attempt to compile the program on OSX 10.10 (Yosemite) using the information here but compiling the required dependency libarea fails with...

ld: symbol(s) not found for architecture x86_64

So unless I wished to go back to a 32 bit OSX kernel (I don't) I suppose that idea appears to be out.