Extended mk2.5 mini rambo box for external driver board

Enlarged stock Prusa Mk2.5 box with enough space for an external driver board with noctua fan. Makes everything nice and tidy and does not increase the printer's footprint.

My heatsinks are quite large and fit fine under the fan.

EDIT: I added Fusion 360 .f3d source file. The other formats available for export did not include the inserted rambo box mesh. Excuse possible bad use of F360 - I am still learning.