I had some fun getting to know the new Inkscape 1.0 and thought for fun I would put it them there.
It's quite possible that this idea has been done before and I haven't seen it but riffing on kkremitzki's comment about the carpenter square and HakanSeven12's more modern logo I made a square and gear idea. I personally like the upper right one. It is still in it's awkward stage and definitely needs more help displaying on dark backgrounds.
I read through the very nice style guidelines but chose to ignore them. Sorry. I I'm just having some fun here and throwing out ideas. HakanSeven12 your civil engineering work benches are what got me into FreeCAD (Thank you for your amazing work!) and as a result am keenly aware that FreeCAD is not just about machining however I think the gear can represent the parametric core of FreeCAD. A tool to do anything. I do think the one I created could be adapted to have more of the sectioned gradients that you have been playing with.
I also played around with a version of the 3D logo concept I previously posted. I don't like it but it is essentially a 3d version of the current logo so maybe has some merit there.