Loose curve from 2 views
With the normal Crv2View command in Rhino, you will create a curve that is not easily editable once created (top image). This is because Rhino will generate a curve that is within your set document absolute tolerance. So the tighter this tolerance, the more control points Rhino will generate.
With this python script, you can make clean '2 view curves', which is ideal if you have to make clean A-class surfaces.
The script asks for two planar curves that are located in two perpendicular views. If the curves have the same amount of control points, and are of same degree, it will return a 3d curve of same degree and point count as the input curves. (bottom image)
You can either copy and past the script below to Rhino for Windows' Python scripting editor, or if you're using Rhino for Mac, use the recommended Atom editor in combination with Rhino Python code completion support, which you can find here. To use the script on a Mac, load the script in Atom, and save the script as Crv2ViewLoose.py. Then in Rhino, run the command StartAtomEditorListener, so that Atom and Rhino can communicate with each other. To run the script, use ^⌥R.