Update 3 of the 3 inch are gone.
I found parts to make four of the 3 inch trackballs less bearings. I do not know if you can take the bearings out of the 2 inch ones and use them for the 3 inch ones but if some one is intrested I will sell the parts for $5.00 bucks so you get 2 encoders, 2 rollers, case, white ball, harness with optics. Please note all is untested. I want no-one to be suprised.
maybe a 2 inch and a 3inch parts can make some one a 15 trackball.