I've been playing with some freehand 3D mapping, using a program someone suggested elsewhere. I haven't tried to be too accurate with distances and scales yet, relying mostly on memory and my own 2D maps to practice making models.
If anyone's interested, I'm using sketchup (
http://www.sketchup.com/), and I have a few files online. I finished the practice model of my old campus' tunnels, it's at
http://freak.minimanga.com/maps/maps.htm Here's some screenshots from that one, and from my next project, a 120 mile, 23 level mine!
UAF Tunnels:
Mine system: