Hi Marco, well the regular ShrinkTrimmedSrf command can be used on a solid already, if you select a solid before you run it, it will shrink all the surfaces of that solid and the output object will remain a joined solid.

If you want to have the output object selected you can change the ShrinkTrimmedSrf.js command to this instead:

// config: norepeat noautolaunch

var factory = moi.command.createFactory( 'shrinktrimmedsrf' );
factory.setInput( 0, moi.geometryDatabase.getSelectedObjects() );

factory.update();
var objs = factory.getCreatedObjects();
factory.commit();

objs.setProperty( 'selected', true );

- Michael