Thanks @balbes for the quick answer.
This is how the bottom box looks like.
The two holes don't show any screw inside, they are empty. These actually have threads to insert some screw in them.
The top of the box is totally flat and has a mirror finish, no sign of any screw.
Neither the sides have any screw.
So, the only places that might have screws are the rubber feet in the corners of the bottom.
But these feel very easy to destroy if I wanted to remove them...
I wrote to stationpc customer support, maybe they shed some light.
Thanks again, you're a legend