Happy to make these complete 
I've had some people ask me if I could make these completely finished. Happy to. But alas I do need to ask for a fee - $45 done to the same design and finish as the one pictured in the fist post of this ad. Fee includes postage. Will be made out of marine grade ply and marine grade varnish - nothing less for this!
As for the naked disk, I need the diameter of the scope's focus knob, and the distance between the visual back and the focus knob.
Installing the disk should just be a matter of a gentle push over the scope's focus knob. It should not be too firm, but neither too loose, but easy enough just to grip, do its job, and be able to be removed without too much pull - you really don't need much effort to turn the focus knob once one of these disk's is installed!
If you are happy to finish off the disk yourself, I'm still happy to supply these just for the cost of postage.