Beginner question: slicing an STL imported from Blender

As my very first step in printing an object of my own creation on my Prusa MK2S printer I have drawn the most basic box in Blender, applied Solidify and Triangulate modifiers (following various advice I've seen on other forums), checked that Blender thinks the object is manifold (using ctrl-alt-shift-M), exported to STL with a x10 scale and added that STL file to the Plater in Slic3r (Prusa Edition 1.37.2 in Win10 64 bit).

The box appears fine in the Plater window, 20 x 20 x 20 mm and Slic3r says that it is maniflold (I've also tried repairing the STL file just in case that helps).

However, when slicing the object I get no useful output in the Preview window (aside from the skirt) and what looks to be a close-to-empty empty gcode file.

Can anyone point me to a list of the stoopid beginners mistakes I might be making?

FYI, print settings are "0.15mm Optimal", with "PLA 1.75mm" filament and "Original Prusa i3 MK2" printer. All the files are attached.

I have confirmed that a random STL file chosen from Thingiverse does slice correctly so there must be something disagreeable about my STL file.

Rob

The walls on your cube are less than 0.1mm wide. You can not extrude that thin.

Ah, yes, I thought I'd tried making them thicker but the other issue was that the Blender interface, for some reason, won't overwrite STL export files and doesn't say so (it turns the filename red and I guess you're supposed to know that means it won't do what you ask it, though it is quite happy to close the Export dialogue box without any sign of a complaint when you press "Export STL"). So quite a few of the things I'd tried I actually hadn't tried at all.

Live and learn. Thanks anyway, I can now progress .