One thing I made for patterning shotgun shells this year was a clear plastic sheet with circles drawn in a 30" dia. and 20" dia. to lay over the patterns.
It allows you to see the shot distribution at different diameters and find the center of the pattern. It gives you an entirely different visual perspective vs a 30" circle just drawn on the paper.
I really really liked using it.
I couldn't find a full sheet of clear platic big enough so I used binder protectors and clear packing tape to piece it together. It was an suggestion I'd about read online so I'm not taking credit for an original idea.
