To make swirly buttons, you will need some plain buttons, cocktail sticks, blu-tack, nail varnish and a bowl that you don't mind making a complete mess of (Yeah, mine is a right mess!), half full of water.
Step 1: Preparing the Pattern
Use the blu-tack to secure an upright cocktail stick to the back of each button. Then gently pour some nail varnish on to the surface of the water in the bowl. You might find that the first few drops fall to the bottom, but once there is a little nail varnish on the surface, the rest will float easier. Add 2 colours, then gently mix them round to make it swirly. Once you have poured the nail varnish, it will start to dry, even in water, so move quickly.
Step 2: Dunk!
Once the nail varnish is swirled, dunk your buttons. It's a good idea to experiment a little, you can either gently put the button just on the surface, or dunk it through the nail varnish. See which works best for the colours you're using. Then prop them somewhere to dry (I stuck the cocktail sticks in a sieve). Leave them to dry. It takes longer than you think, don't move then for a good hour or so.
Step 3: Finishing Them Off
Once they are done, you may need to use a cocktail stick to tidy up the buttonholes.
You can try the same technique with other objects, such as plain earrings, or nails (caution, this is really really messy!)