I got the highest res reference I could find for mine, and found a group of pics from someone's repair workshop that showed the Horn from loads of angles.
Then I just gave it weeks and weeks of time - think it took about 5 to get the whole lot modelled doing a little bit every day...You did very well to get yours out in 2 !
What I do, instead of rendering Isoparms with S&T is slightly annoying, but it does work.
In the Object Manager, search for SDS, and then set all your SDS objects in the scene to 1 and 1 (viewport and render subdivisions). Then choose Standard Render, and in the settings, add Cel Render, and tell it to only do lines, not outlines, and set colours to black and white or the reverse. Render out your cel render wireframe, then combine with beauty pass in Pshop or similar using overlay or screen modes... not quite isoparms, but looks enough like it to pass, and no annoying dots...
This was done like that, except I also did a cel render with SDS set to 2 x 2, and set that layer even lower in transparency than the 1x1 file, which gives a nice 2-tone effect...
CBR