Draw a collar pattern or search for one online (just google "peter pan collar pattern", there are plenty available). Place and pin your pattern on the felt on a fold (as poorly shown in the pic) so that when you cut it, you get one symmetrical collar piece.

Place your collar on a flat surface and start placing the studs on the collar as you want them to be. When you have a plan, start attaching them using pliers or just fingers.
Continue until your design is finished.
This is the most time-consuming and finger-hurting part so I suggest watching a good movie during this step. (:

The backside of the collar is now full of the sttachment spikes that get caught in your clothes and hair so we want to cover that up with another piece of felt. So cut out identical piece of felt . If you're using a contrasting color like I did, cut it a few millimeters (~1/8 of an inch) smaller so it doesn't show on the right side.
Glue the felt onto the wrong side of the collar. Remember not to use too much glue, it makes the collar a bit stiff. If you don't want the stiffness of the glue, you can also hande sew it on place.

Take your hook and eye and hand sew them on place. Make sure that the pieces are on the same height and meet up in the middle

Enjoy your awesome, one of a kind collar!