I have am doing another "honey do" chore for my wife putting in a bunch of 6" cans. I have a cutter that fits on my drill that does a good job on the 4". No joy on 6" tho.
I experimented with a box knife blade on a stick of wood with a center pivot hole into a screw in drywall anchor. That seemed to work OK for scoring the paper but as the blade got a bit deeper it was gouging out the hole (flat blade, round hole thing)
I guess there is an attachment for a rotozip but I don't have one and I am hoping she gets over this can thing soon.
I was just curious what the real tool was.