Compatibility

Once you have your piece, you will want to use it elsewhere. As mentioned above, FreeCAD can import OpenSCAD models, but FreeCAD can also export to OpenSCAD. However, the results are not very satisfying, as FreeCAD reduces your part's whole body to a single polyhedron. With even only slightly complex pieces, this translates into a list of hundreds of vertices and faces, which are very difficult to edit.

FreeCAD supports photorealistic rendering from the Raytracing workbench… sort of. You can use POV-Ray [6] from inside FreeCAD as long as you install the povray utilities. However, POV-Ray hasn't been updated since 2013 and is, to put it mildly, slightly antiquated. The other alternative FreeCAD offers, LuxRender, currently doesn't work, since the LuxRender project has migrated to LuxCoreRender [7], and the FreeCAD team has not caught up yet.

Your best choice is to install the Python pycollada module on your system:

sudo pip install pycollada

Export your objects to a COLLADA [8] file, import that into Blender [9], and render from there.

Exporting for 3D printing is as straightforward as you imagine: Export your file to STL, open in your favorite open source slicer, and generate your G-code for your printer.

In all of the cases above, for the exporter to work correctly, and since you can have several pieces at any given time on your workbench, you have to tell FreeCAD what you want to export. To do that, select the objects you want to export in the Labels & Attributes list before starting the export process.

Conclusion

I know I say this a lot, but… FreeCAD is great fun! Some of the features and workbenches are rough around the edges and the learning curve is not at all flat, but the CAD power it brings to Linux is pretty sweet.

Besides, there are plenty of guided tutorials on the FreeCAD wiki [10] that will help you get up to speed designing your own parts in no time.