Customizable D6 Holder (Multi-dice)

I want to use the [Customizable D6 Holder](https://www.thingiverse.com/thing:783285) by [cdcrockett](https://www.thingiverse.com/cdcrockett/about) for wound counters in Age of Sigmar, but many of my units have more than 6 health. This is a modification to the aforementioned D6 Holder that adds support for 1-4 dice.