I once remember watching Blue Peter make a candle and it looked fantastic as every one is unique.
You need:
Clean baked bean tin
Large heavy glass ashtray
One tall(ish) candle
Broken bits of other candles, of different colour if possible
Pliers/Oven glove
Washing up bowl/bucket of water
Melt a little of the tall candle and secure it to the centre of the ashtray. Melt down the broken bits in the baked bean tin(leave the lid attached).
Once melted, pick up tin with pliers or oven glove(using the lid) and pour the wax into the ashtray.
Then, carefully hold the ashtray just above the bucket of water. Take a firm grip and just as you release the ashtray, spin it as it drops into the water.
After a few minutes the resultant candle can be removed from the ashtray.
The results can be spectacular, particularly with contrasting colours.