Not exactly, I start with aprox 1.5" x 1.5" square of paper, put a similar or slightly larger piece of tape on one side and roll it into a cone.
First pic, 1.5" paper square with piece of duct tape attached on one side ready to roll.
Second pic has the paper rolled into a cone around my thumb. At this point you can make it any shape you like. Long and narrow, short and fat, or somewhere inbetween.
As long as the tape you use is wider than the paper, it should always cover it completely.
And here is a finished cone, ready to be marked and trimmed and glued. Takes longer to take the pictures than it does to roll up the cone.
Ready to be trimmed to size and mounted on your dart of choice.
Paper gives it stiffness, tape gives it water resistance and flexibility.
And doing them the way I showed makes it very fast and easy to do with this big fat old fingers of mine.
I've tried several kinds of paper, mostly what I use is post it notepad cut into pieces.
I've tried several kinds of tape, mostly what I use is plain jane gray duct tape.
For darts that I want to remain perfectly centered and last a long time I'll mist the inside paper lightly then drop in a couple drops of gorilla glue. It foams up locking it into a solid mass filling the cone halfway or more. Just make sure you have it straight.