Holder for Prusa i3 MK3 hex key set

Customization of [Arbitrary hex (Allen) key holder](https://www.thingiverse.com/thing:2988075) to fit the keys included with the [Original Prusa i3 MK3 Kit](https://shop.prusa3d.com/en/3d-printers/180-original-prusa-i3-mk3-kit.html).

* 3 mm
* 2.5 mm × 2
* 2 mm
* 1.5 mm × 2