I tried a different approach to the 3D design challenge for the curved frame: create a set of full curved layers to build the geometry of the required circular section, to the extension of the frame, thencut it through in the middle with a cylinder sector.
Being symmetrical, it’s enough to build a quarter of the frame and then mirror it. The required frame section must be sliced in three layers, corresponding to the horizontal lines in the picture above. Each layer is as long as half of the straight side length and must be swept along the curved side of the frame. All the sweeps start from the middle of the curved side, on one of the reference planes (I choose the x-z plane for the sketch and the x axis for the revolution), where the two symmetric parts of the final frame will be attached together. The geometrical small challenge now is to compute, for each layer section, both the radius and the extension of the arc of the circular section around which it must be swept, to generate the right profile on the straight side. 
The only references I had were the radius of the inner part of the more external dent (in green here besides) and the length of the straight side. As the frame should be square-like, starting from the side length (l), with the inner radius (r), it’s easy to compute the arc of circumference needed to have the same length (360*l/2πr) on the curved side. I drew the sketch on the x-z plane at the proper distance from the revolution (x) axis. The more external layer is then quite straightforward, as in the picture below, superimposed on the section sketch.
Revolving it around the x asis for an arc of the above computed amplitude, creates the more external layer.
The intermediate layer layer must be created in two steps: a thicker layer longer layer from which a shorter thinner layer (corresponding to the right side lower dent in the picture) must be cut out (the right side of all the layers coincide with the middle point of the straight side).
To create the same indented profile al
ong the straight side, this layer must be swept along an angular amplitude which is less than the external one of an amount corresponding to a circumference part as long as the dent, using the same formula as above to extract the arc difference (arc_diff = arc_complete * dent_l/side_l).
Now it’s time do draw and revolve the innermost layer to cut out the internal dent from the just created layer (as the others, matching the same side length at the right side of the sketch, out of the picture).
Again, the sweep arc is shorter w.r.t. the previous, of a distance matching on the circumference, the horizontal distance in the two dents. In the picture here below the internal layer is show as wireframe, while the thin coloured layer is the newly generated to be cutout from the previous.
The quarter of the frame is now ready with the proper shape:
It needs only to be cut through in the middle: again, a sector of cylinder with the arc amplitude matching the horizontal upper extension of the section sketch does the job: here below the quarter of the frame and the detail of the straight side section: the profile of the original section sketch, just “curved” to match the cylinder shape.
Even if this solution required more time and some geometrical computations, I’m more satisfied of it’s elegance, w.r.t the previous one. The final result, of course, is the same.
metric profile.
The generated half straight side will perfectly match the curved side at the corner, but will end with a 45° sloping face, which will completely intersect and overlap with the corresponding ending in its mirrored copy.
The fun comes when trying to add the company name and logo: the extrusion of the company name needed just a resizing and positioning, while the gearwheel logo has been more tricky. My idea was to include the core of the gearwheel design in the id badge, keeping it “low relief”. As in the business card the gear appears tilted and turned, I tried to reproduce the same positioning in 3D, I cut out from the badge card the tilted and 
turned extrusion of the full twisted gear and then I inserted in the cutout hole a thin slice, cut symmetrically around the plane where the inside cut changes shape, as well positioned and tilted. After adding a cutout hole for the clip badge holder, I sent it to the printer. For this first print run I choose to engrave the company name (as an alternative of having it also as low relief) and to use white resin.
The original object is too big to be used directly in the 3d badge. As FreeCAD does not offer so many options to manipulate stl objects (as, for example, Blender does), I decided to generate the same gear using FreeCAD tools (and to consider it for me a challenge to learn more FreeCAD features tipps and tricks, instead of a “not so skilled” way to complicate my life as a designer when a clean and easy way as software developer would be at hand 😉 ). I had available the section of the gear in svg format, easy to be imported inside FreeCAD, but as FreeCAD does not offer yet the possibility to twist a surface while extruding it, I had to find a different way to build the twisted gear.
I created an “ortho” array of “lofts” elements connecting two copies of the same “polar” array of the single “tooth” of the gear. This is really building a whole from the single element 😀 . (Yes, I’m aware of the one code line with OpenSCAD, but where would be the 3d designer fun? I would have been the same proud as a coder, had I written myself that one code line…). No need to enter details about the inside cavity: a cylinder and a cube used as cutout tool for a Boolean “difference” with the gear.
Then the idea came to my mind to design a 3d corporate badge, to gain more company visibility when we are at the FabLab workshop, printing our prototypes, or we take part to workshops, sharing ideas with other professionals. Wanting to keep the same appearance of the business cards, I asked 
ame shapes in 3D with 
wrong node in the agglomeration is kept in the import. This made a lot easier to h
ave all the letters as surfaces and extract the internal cutout surfaces (for letters like “P” or “D”) to create by boolean difference the exact text-shape to be extruded. 
