Here is a really easy DIY which I use often. I layer the necklace over everything from coloured jumpsuits to logo tees.
For this project you will need some rhinestones, E6000 glue, a wooden skewer and a plane bib necklace base. I got mine from Far East Plaza in Singapore.
Simply place the rhinestones on the bib and glue in place your design. I then layer it over other necklaces: