I chanced upon this awesome project on cutoutandkeep's blog, under craft finds, and I mean, other than the really poisonous fumes, this project is really worth it!
First you gotta attach your bobby pins to a piece of cardboard. Then you start applying layers and layers of bright/neon and colourful nail varnish while allowing them to dry between each layer. You might also want to apply a top coat to protect the varnish!
After all that drying, (and I suggest leaving them overnight to prevent yourself from breathing in too much fumes), play around with your bobby pins and create your favourite colour combinations! Feel free to add more pins of the same colour, or break the chunks of pins and use them individually to create a more natural feel!
And! When you're finally satisfied with your combination, slide it into your wire necklace and yay! You got yourself a new, pretty necklace! You can choose to further customize it by adding little details, stripes, polka dots even! Have fun and enjoy your beautiful creation!