The trick is to make all the colored part of the auricle compatible in terms of edges so they can be connected by bridging edges or by merging vertices. If you are about to follow my instructions step-by-step I strongly suggest you make your own blueprint by imitating Fig.01. That way you will have better understanding of the auricle anatomy.
To set an image plane in modo 401 you have to make a new backdrop item and in the image selection, choose "load image" and load your blueprint. You will also have to set Projection Type to Left because we are working with the left ear. If you do this properly you will have your blueprint loaded as in Fig.03.
The next thing to select is your backdrop item and offset it on the X axis. That way the blueprint won't stand in your way when you model is in perspective view, but will still be visible in the viewport.
Modo 401 tip:
You can drag and drop any image from your explorer directly into the viewport to make a new backdrop item.
Now the backdrop item is ready we need a new item; this time it's a mesh item. Again make a new item and choose "mesh". This layer will contain geometry for one of our six major auricle parts so let's make the first part. Since the backdrop is set to left projection, go to the left corner of the viewport and set the view to "left".
Now let's set the options for the Pen tool. On the left side of the modo interface you will find the modeling tools and under the Basic tab select the Pen tool. In the Pen options menu change the Type option to Polygon and check the Merge and Make Quads options (Fig.04).
Now you are ready to make some geometry, but before you jump into tracing out the polys on your backdrop I suggest you try some free runs with this tool to figure out how it responds.
When you are ready to do some modeling, trace your blueprint with the Pen tool by following the red lines. When you have traced out one of the six major parts press the Space key to drop the tool and re-select the Pen tool to begin the next part. Repeat this process until you have traced all six parts. When you have done this you should have something like Fig.05.