Materials:

Medium melt point wax for pillars (around 135-140)
Additive of preference (stearic, vybar, etc.)
Candle dye/color
Fragrance oil(optional)
Pillar mold (any size or shape)
Wicking for pillars in appropriate size
A coffee can or bucket (container deep enough to dip in)
Poster paints or any oil based paints
Borax(from the laundry detergent section)
Chopstick, knitting needle, etc.  (some sort of long stick)

Instructions:

1)  Pour any molded candle in any color you want (scent optional).

2)  Put enough water in a container (bucket, coffee can, etc.) to completely cover the candle when dipped.

3)  Surface tension in the water will cause water droplets to form on the candle but you can avoid this by using Borax.  Put enough Borax in the water so that when the candle is dipped you have very few or no water droplets.

4)  Then use poster paints (any oil based paint will do) on the surface of the water.  Drop them in in a swirling pattern and swirl them with a stick of some sort,  like a chopstick.

5)  Then dip the candle in a twisting motion.  When raising the candle from the water blow the paint away from the candle or the design will be distorted.

6)   Dip in clear wax to coat and protect the paint and give the candle a finishing touch.
 

Good luck and happy marbelizing!