I had seen this before, but was being lazy and didn't want to venture too far into CAD all alone. After some more searching, i took the plunge. Downloaded openscad, played with some numbers and I have a plate printing as we speak. Took 10 minutes to figure out including measuring my plate for dimensions. Very easy having a template laid out like that.Here is an openscad design your own. Interested to see how well this one works.
Index Plate by buffcleb
Create custom index plates for use with dividing heads and rotary tables. All settings are customizable so this should work with many different dividing heads. The default settings were designed to work with my 6" LW Chuck Dividing head.This is my first openScad project so It'll probably change...www.thingiverse.com