You will need pliers, wire cutters, dowel or knitting needle and 14 or 16 gauge wire.
Cut a piece of wire about 18" long. With pliers bend wire into a u shape about 3" from one end.
Make a 45 degree bend about 1" from the end of the short end of u shape.
Hold the u shaped looped end with pliers and use the wire you just bent to wrap around the loop.
Using dowel or knitting needle, bend the loop into a hook.
Using pliers, turn up the end of the hook. Use pliers to shape hook.
From end opposite of hook, thread on desired beads. Be sure to choose beads that have an ample opening. I like to use small beads on each end of my beads. This helps to keep all the beads from sliding around. Once you have all your beads placed as you like, use dowel, knitting needle, sharpie etc to make a loop or double loop for the spring.
Since using the pin on a garment may take up some space in the pin, be sure to leave enough wire to go past the hook a bit. I would leave at lest 1/4"
Shape as you like and if desired you can sharpen the end with a metal file but it will easily go through most knits as it is.