But i refound that! (with the complicity of Patrick ;)
so cost = 0 $ except for Autocad & Moi if more than simple export DWG needed on another process wanted! :)
SketchUp Make free on local computer is now only SketchUp Make 2017 : https://www.sketchup.com/download/all/

(Moi export) --> Format Skp --> DoubleCad -->DWG ---> Autocad (Briscad etc...
(take export SKP V 8 for more compatibility)

So can be directly Moi --> DoubleCad --> AutoCad etc... :)