Arkon car mount extension arm

I have an Arkon universal cell phone holder (http://a.co/5GsdtQw) in my car, but the stock arm just isn't quite long enough, so I designed this extension arm, 100mm center to center vs the 70mm of the stock arm. Adding the teeth on the one end to keep it from rotating was fun, and it actually worked. This is a first pass, and I designed the arm to be straight for simplicity's sake.