Working out the size of the holes wasn't too hard .
There is red disc and a yellow disc .
I do have the red one , so measuring the holes and size is simple .
It's the yellow one I want , so I found a picture of lens with the yellow one in , and took a picture of the lens with the red one in .
With both printed so they are at the same scale I was able to measure the large centre hole on both , and both rings of holes ( two sizes ) .
Measuring off a picture threw the lens element alters the measured size which is why I measured the discs of both so I had a sense of scale and the red disc as a reference .
Drilled out right , you use the aperture scale on the lens , one for the red disc , one for the yellow disc and one for the lens without the discs .
You obviously have to drill the correct amount of holes , and at the right distance from the centre so the dont overlap the edge of the glass element .
Fortunately it worked out that I could buy drill bits that were the right size for the small and medium holes . I just had the main disc cut to size on the inner hole and outer dimension .
The discs and holes are different on the smaller 180mm SF , so wont help the OP .