Mirrored object

 From:  Michael Gibson
2130.2 In reply to 2130.1 
Hi Mike, that probably means that your new object is not a
fully closed solid.

Somewhere there is a hole or some edges that did not get
joined to their neighboring edges.

If you are using the latest (Sep-21) beta, you can use this script on a
keyboard shortcut to highlight the open edges:
script:var gd = moi.geometryDatabase; gd.deselectAll(); var breps = gd.getObjects().getBreps(); for ( var i = 0; i < breps.length; ++i ) breps.item(i).getNakedEdges().setProperty( 'selected', true );

Also if it looks like your object should be closed you may try just selecting
it and using Edit/Separate on it followed by Edit/Join to re-join it and
possibly seal up the edges that did not get joined properly previously.

Other than that you would usually use the "Flip" or "Reverse"
function in your other polygon oriented software to reverse the
direction if it is not what you need.

I do have it on my todo list to add some kind of option for displaying
normals and flipping them at export time from MoI but there is not
currently a way to do that.

- Michael