I also print my own track. I can use CAD, but instead I bought a membership from 4DBrix and download their designs. I pretty much just stick with elements that TLG does not produce, for example I am currently printing myself Wye-Switches.
I am also working on printing a new car coupler... I don't want to go into more detail until I have a finished version to show off. But is there a place here to talk about 3D printed parts for use in LEGO builds?