I have a couple of choppers, and they are consistent and productive...however.....once I started using different profiles, I knew I could not afford a new chopper for each.
I started free-hand cutting with scissors - it works but sometimes is not very even.
I made a template from either cardboard or heavy plastic sheet like a tupperware lid etc. I either used scissors or an exacto blade to follow my template. This worked better IMO but not 100%.
Now here's what I do..lay the fletch flat with the quill along a flat edge for consistantcy. Then I use masking tape to tape the fletch flat. the secret here is the tape also holds the feather barbs in place for a consistent and nice smooth cut edge.
With a fine pen or sharp pencil I trace an outline of my fletch profile from a template like before directly onto the masking tape while lining up the base straight edge with the straightened quill.
Once thats done , pull up the fletch with tape still attached, and trim to the template outline with nice sharp scissors.
Easier to follow a nice outlne and the barbs don't shift on ya. Once trimmed out, just peel off the remaining tape left attached covering the fletch and theres your nice smooth trimmed fletch. This worked real well when I do English style fletch, but I also modify several templates for a more or less shield cut or Pope-Young style.
But thats just me...