Hi eric, check out this previous thread for some different possible techniques:

http://moi3d.com/forum/index.php?webtag=MOI&msg=3859.1

There are a couple of different strategies that you can use depending on exactly what you want to get.

One way is to do a sweep to build a tubular type shape, and then boolean that shape away from the main piece, cutting a groove in it. Doing a sweep around your lines is the way to basically give them thickness and depth. To get the path lines on your object you can either project them on to it or if you've got planar surfaces you can draw lines directly on the surfaces using the polyline tool in the 3D viewport.

Another method is to focus more on splitting your object up into different faces, using either Trim or boolean commands with some 2D curves as the cutting objects, and then use either the Inset command with the "Grooved" option (see link above for an example), or maybe fillet or chamfer the edges depending on what exactly you want.

But hopefully the above link (which has some other links in it as well) will give you some ideas.

- Michael