Flame. Lighter, candle, etc. No scissors, razor, etc. NO CUTTING, that is why they are called burner.
Feathers, you place a feather in the pliers, trying to put the vain either in the middle or off to one side. Hold it with the burner and run a flame around the outside. You end up with a perfect wing, and yes in pairs.
With man made material the placement is not important, just don't let it move once in the pliers.
The stencil or the ones that are cut are WING CUTTERS
Some things are better left alone, Even though, some feel they know better.