FreeCAD
I've been reluctant to jump into 3d design for a few reasons. Primarily, the open source options are bad. Today the king of hobbyist CAD is Fusion360, but I refuse to learn a tool that can be taken away from me on a whim.
There are few open source alternatives. OpenSCAD lets you describe your 3d primitives with text, adding and subtracting faces or writing code to handle transformations. I like the idea of keeping my models in a git repository but the few times I've tried it I found it awkward. The recommended way to do fillets and chamfers in OpenSCAD is to export your model to FreeCAD, make the change there, and then import it back.
FreeCAD is like a herd of warthogs hidden under a parachute. It's a single program containing dozens of workbenches. These specialize in architectural drawings, finite element analysis, animated mechanical assemblies, and a half dozen workbenches are for designing parts.
FreeCAD has two different approaches for modeling parts. Each has a gang of rabid users who refuse to settle on a single method. Just read this discussion about an effort to remove one of the two ways to create a sketch.
The FreeCAD developers are well aware of this problem and have been doing a ton of work to herd these cats/warthogs into consensus. See the huge list of open issues. Surprisingly they might actually be making progress. They released version 1.0.0 in January 2025.
Shamara recently got a 3d printer and our local library is setting up a maker space, so I decided it was time to learn FreeCAD. I found a simple project and spent a painful ten hours wrestling with the interface. I wanted to create a single rectangular solid with a few holes and a some detentes, involving, in total, less than 10 primitive shapes, but it was so difficult.
The FreeCAD project has a wiki, but it was down when I tried to do this and google returns results from FreeCAD v0.14, v0.20 and v0.21 with warnings that things had changed significantly between versions.
I had a few problems learning the tool. The getting started guide (like everything they have several poor options rather that one really good one) wasn't well written. They didn't make it clear how important it was to fully constrain your sketches, and they should have chosen a model that required a datum plane to show how to create a sketch in arbitrary space. But my biggest problem was with the modal sidebar and a bad color scheme which made it impossible to tell when a line or point was selected.
When I realized I had a problem with the color scheme and not the default setting, I tried to change the color options in the preferences, but they didn't seem to have any effect. After hours of frustration I hit the 'reset all' button in the preferences and everything became much better. I think I had a configuration file from an older version of FreeCAD and this old file completely broke the updated application. Normally software would attempt to fix the config for you, or at least give you a warning that the old configuration was incompatible, but instead they decided to just fail.
I hate video tutorials. The instructors dither, trip over their words, and often spend too much time explaining things that are obvious. But I admit they're useful for visual utilities. When I was designing Crazy Chef in Inkscape I found a good video channel that helped me get on my feet.
Here's the video channel to follow for FreeCAD v1.0.0. He shows how to fully constrain your sketches, create 'datum planes', and demonstrates 'additive loft'.
For me, the promise of 3d printing has been for making toys and cheap replacements for broken plastic things. Oven knobs cost $80-$120 if you buy one from the manufacturer. Now I'm reasonably sure I could design my own.
I can recommend FreeCAD over fusion360 if you're unwilling to trust a for-profit company, but be sure to reset your preferences, stick with part designer, don't mess with the sidebar modal settings, fully constrain your sketches, and watch a few video tutorials first.
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