I have been futzing with this and it's very touchy. Some fonts work, some do not. I can normally bend NURBs to my will but I can't seem to find a consistent workflow for this.

Once again if you care to upload your curve I'll see what I can conjure up. To be honest this exercise might be more suited to ZBRUSH.

As you intend to use this for STL printing the density of the mesh or topology is of little concern. The mesh just needs to be water tight. Just make it dense, boolean it, and remesh.