Hi nikola, the first thing I'd check is if the object is a solid in MoI or not, you can do that by selecting the object and looking at the object type indicator in the upper right area of the window, does it say "solid" or "joined surface" ?



In order to be 3D printable, the receiving software for the printer will expect that the object is a closed solid.

If it's not a solid in MoI that means there are openings in the object that are stopping it from being "watertight". You can find where the openings are by using the highlight naked edges script from here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2

It also looks like you may be sending multiple different objects in one batch, you might focus on just one individual object per stl file, and also it looks like you have some small scale details in the model which could be smaller than the build tolerance, those features might need to be removed or simplified in order to get a good print.

You might also use an STL checker program like MiniMagics to load your STL file and show problem areas.

STL processing is in general far more finicky and sensitive than rendering and your model needs to be cleaner and simpler in order to be printed than it needs to be for rendering.

- Michael