Hadn't seen anything like this...so I made em! AR500 waterjet cut targets with an inch grid etched into them VERY shallow. Looks like a standard plate through your scope, up close you can get an estimate of group size almost instantly. Prices are only $50 for a 10" gridded, and $60 for a 12" gridded...lower than any other plain waterjet cut plates I've found.
Also did some full size IPSC with scoring zones etched in:
I would think that if you started with black spray paint and then rolled over it with white you might get the desired effect.Those are great! I'm wondering f if you could use some dark chalk and rub it across the plate and see the lines? Or use something else? lightbulb