Thank you, both
I used MoI trial till it works: it goes fine for small models. To have a good result (without errors) with mine I had to divide it into 4 parts.
About Sycode I knew of it and I asked a key two days ago: I let you know how it works.

Hi everybody,
I'm a student an I usually draw my models with Rhino. For an exam I need to import a model into SketchUp but using .3ds format I have lots of errors. Does it exist a way o a plugin to import a 3dm model correctly into SketchUp?
Thanks