20v portable tool holder

Remix of the original; two big changes:

I removed a notch on the opposite side and slightly increased notch size. This allows the following tools to work with this:

* 20v Porter Cable
* 20v Black and Decker
* 20v Crafstman 20v Max
* 20v Stanley FatMax
* 18v Bostitch

I also resized the overall mount to be approximately 82mm tall, as this mounts better on the wide face of a 2x4.

Update 3/29/19: Made a bit smaller and changed orientation. Print standing up. Infill can be as low as around 10% as long as you use plenty of walls (I've been making them with 4 walls, 4 top and bottom, 10% infill).