@squarewhite said:

Is there any plugins or extension that allows sketchup users to set a folder as the place where sketchup is supposed to save your skb files ? I find annoying to have so many files in my folders. For Autocad users, i suppose that i´m nostalgic from the MOVEBAK command line.

It will always make the SKBs in the Model's folder.
You can switch off backup making in Preferences.
If you do that but want to still have some comfort that your precious concepts are safe from crashes etc then as well as making regular saves find my Archiver.rb script [ http://forums.sketchucation.com/viewtopic.php?p=149749#p149749 ] - this loads Archiver into the File menu - you can easily shortcut key to it, so then pressing a key before you make any major changes will make a silent backup into a folder called Archives - the Archive file is named as the model_name[yy-mm-dd-hh-mm-ss].skp so you can readily work out which one is which. Unlike SBDs earlier versions are not overwritten and they can also open directly in SUp if desired. Also the Archive is a snap shot of your model as it was at the exact moment you make the Archive - not the last 'saved' version - unlike an SKB which is always the previous saved version. There are also some other useful Archive tools added to the File menu - one opens the 'Archive Folder' and another is an 'Archive Option' - this makes an Archive of the model as it stands that second and then lets you save a version of it as model_name[Option_1].skp and carry on working on it with perhaps alternative ideas, without loss of the original scheme...
Archiver isn't for everyone, but some find it suits their workflow much better that SKBs or even save_as'ing...