Kossel Rod Jig M3 Bolt

The original kossel rod jig for open beam was for a different traxxas fisheye ball end. I had original modified it to fit the kind I have by thinning the center pin and widening the head a bit. But It seemed the center pin would be a bit fragile. So I remixed it to take a M3 screw and nut. a 16mm M3 screw should work great.