For POLAR, I went with the "polar opposites" concept. I don't know if this turned out particularly successful in that context, but I basically served myself with the challenge this week - - I really justneeded to do something loose and fun, and although I started out with the concept of "polar opposites" as my engine, I veered off the shoulder of the road a bit. But as long as I am productive, I'm happy. It's been a little difficult to maintain focus on one project lately, so even just completing a quick little painting without overthinking it, overworking it or over-worrying about it, felt refreshing to me.
About the medium: I used a nib dipping pen instead of my more-often-used Rapidograph technical pens, so the line is not uniform.