Has anyone made their own charms / keychains?

[Pheasant]

Unless circumstances dictate otherwise, I will be attending a craft fair near the end of the year. I'd love to make some 2D keychains or charms to sell, but I have no idea how to make them! I'd prefer to have them printed on vinyl, although I will consider other materials if nessecary. Anyone have ideas?

[Sukey]

Blank Shrinky Dinks are always fun! Even though the kind I have isn't made to used in a printer, I have done it anyway. It just comes out really light and you have to fill in the color with sharpies or colored pencils.

[thesugarpuppie]

I've never done vinyl but I have made them with laminated cardstock and hung them on ball chains for 2d.