Actually, creating a high quality 3d model from the K402 would not have to be very expensive. All you need is a decent (DSLR or System) camera, a tripod, appropriate professional photogrammetry software like: Autodesk ReMake, Agisoft PhotoScan, RealityCapture, or 3DF Zephyr and a workstation. It's not that difficult to convert a point cloud into a useable CAD model.
Arash, with regards to horns in general and specifically: tractrix horns and waveguides, I have read other threads in which you share plans and experiments with Faital Pro drivers, the LTH-142 horn as well as the 18Sound XT1464. You have also expressed a preference for the XT1464. As I am working on a similar Klipsch / Altec inspired 2 way, I would be interested to learn the aspects in favour of XT1464. By the way, I share your preference for phenolic diaphragms over titanium. Therefore, the HF146 is on my driver shortlist.