Thx for all this proposals, for the moment you are the first who propose a symbol attached with the log.
I would like to explore this idea.
Could you integrate the notion of construction as I ask in my post.
May be you can introduce a laser nozzle above symbol in construction as this :
http://blog.lefigaro.fr/bd/assets_c/2011/08/gantz-photo-1-thumb-598x315-34602.jpg.I don't really know if it's a goo idiea :)
Thx