I have used spring stem rings for years, but don't have a flight punch and have never used slot punched flights. I'd slide the rings onto my nylon shafts and then put the flights on. It's always worked okay, but not great, as the prongs of the stems don't close up tightly, flights still pop off regularly, and shafts can be robin hooded pretty easily. Last night, being a bit bored, I decided to figure out how to punch a slot into my flights for stem rings. My solution was quite simple. I found a bobby pin ( I have daughters so lots of bobby pins in the house) with no plastic tips, and with a width that is pretty close to that of a spring stem ring. I took some pliers and made an L at the end of one of the legs. The foot of the L is a tiny bit shorter than the diameter of a stem ring. I heated the L, and when it was hot enough pushed it through a flat unopened flight. I didn't do any measuring or examine a punched flight, I just eyeballed it and made a best guess as to where to make the hole. I was lucky. My guess was good. First one a bit messy. But worked. Second try better. Third try great. A pretty clean, neat rectangular hole. I trimmed a bit of the plastic around the hole with a knife. I inserted the ring, opened the flight, put it on my nylon shaft, and secured it by pulling down on the ring with my fingernails. Beautiful. The ring holds the prongs of the stem really tightly against the flight. No flight punch, no problem.