Export STL for 3d printing

luckily i found a very nice Modell of Mount kilimanjaro in the warehouse.
the size of the file is something around 6MB. when i Export it as stl for 3d printing it Ends up with 600KB.
the Polygons are less and the Modell is very rough.

how can i manage to Export the full Resolution of the original skp file?

hope to learn something

thanx guntram

For 3D printing, you need a solid volume, you can make it like this for example…

i agree with you that i Need a volume to print.
you think or better you know that the “completed volume” will improve the exported Resolution of the surface?

your Picture and the time between my question and your answer leaves the Impression that it is just very easy to get the volume result.

do you have any "quick “hints” how i do it myself?

The model isn’t very detailed so you will get a rather lowpoly stl from it. The author made a note that it isn’t accurate.
If you want a smoother finish you could use Artisan as I have done here.

I’ve only used the line tool to create that skirt.