I feel moderately fluent in FreeCAD by now, and what you describe seems very simple and quick to me; would be a bit faster for me in FreeCAD than in OpenSCAD. But not trying to talk you into a switch, and direct STEP output from OpenSCAD seems like an awesome addition.
Extrude a bar, pocket a V-notch, multi-transform to make a linear copy and then mirror it. (There are other ways depending on how it's intended to be arranged, I imagined it centered.) Took less time to model than to write the this description of how I did it... ☺