Pen and Ink Challenge #6-10

I haven't been able to post sketches from the last several days as Dad's been away with the camera. 

If you draw a squiggle so that the lines cross each-other anywhere except at a crossing of two lines and colour alternate shapes, it all works out evenly without exception.

Really, I play the violin every day but you would never guess I even know what one looks like from these sketches! 

My fountain pen gave out

So I used brush and ink for the next one

And a rather uninspired one with a pen which was running out of ink.