Been working more on this sketch, trying to make it better.
I've changed the color to show that it's been worked on more and not just a duplicate sketch.
I've blended the bristle brush quite a bit more, added and refined highlights, shadows and a few other details. Spent another hour on it. That's 2 hours more than I usually spend, on average.
Here's the first one: http://app.sketchclub.com/sketch/10996497