I just cant copy those projects cause I dont know the bars size and if I want to scale it I have no idea if it will work
I found this solution: http://makerarm.com/
I think this approach (makearm) is WAAAAAY better than most "3d robot arm" projects around cause it has veeery feew linkages and it's so simple to build and the pencil will always be vertical, without any mechanism.
Does any of you know any disadvantagem of makearm related to the common 3d robot arm approach (which I provided pictures in the first post)?