Hi Guys, Basically what I am trying to do is come up with a solution to design a jig for different plastic parts for automation purposes. These parts are toy helmets, all of which have different shapes and sizes,but have a common inner diameter where the head of the toy will be held. The main reason a fixture is needed is to measure the inner diameter of the helmet. Constructing a fixture for each of the 20 parts is not feasible and therefore I was thinking of construct a jig similar to a collet which can hold different parts. The only problem being that the orientation of the inner diameter of the helmet has to be perfectly horizontally so that a vision camera can take a reading. Any help with this problem is truly appreciated. Regards, Neville.