I have 3 sets of brass feelers for doing this ignition gap function. Not that unusual.

https://www.ebay.com/itm/Performance-Tool-W80526-6-Blade-Non-magnetic-Brass-Feeler-Gauge/401333029502?epid=1539519277&hash=item5d71500a7e:g:8SIAAOSw8lpZJJJF