Fusion 360 is a very good CAD/CAM system which is free for “hobbyists and startups”. I’ve used it a bit to make some mold designs, and it’s quite good. It’s currently the best recommendation for free CAD/CAM software.
It is offered free for “For startups generating <$100k/year in total revenue or wholly non-commercial users.” Here’s the details on getting your free license: https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-activate-start-up-or-educational-licensing-for-Fusion-360.html
See Molds and cassettes for some examples of Fusion 360 in action.