When I was a girl we often went to the Renaissance Faire in Southern California. It was the 70's and they usually had some cool crafts to create for children and adults alike. (This was before the faire moved out of the beautiful foothills of Agoura and was forever altered by the sponsorship of Budweiser or some other such major manufacturer.)
Anyhow, I remember once making a huge multi-wicked sand candle with blue wax when I was very young. I got to carve a shape in a big box of sand, help put in the wicks and pick the color wax I wanted. I had that candle for years and would never light it because I wanted it to last forever.

When I was trying to think up crafts suitable for Summer this recollection came to me. I figured working with sand was seasonally appropriate and thought Naiya and I could do this one together. We started small. The candle seen here that we made was much less funky and tiny compared to the one I recall. Partly this was due to not being overly familiar with candle making. Mostly though, we kept it small and simple because we didn't have very much wax to work with. When I get my hands on another block of beeswax we'll go for a larger, hand sculpted, more elaborate design.
We began by filling a bowl with sand and moistening it slightly. The water keeps the shape from falling in on itself but the more water used, the less sand will stick to the wax. (Naiya had the spray bottle and got the sand much wetter than it ought to have been so, in the end, our sand candle was not very sandy at all. Keep this in mind if you'd prefer a thicker exterior wall.)
We then used a small vase to make our candle shape. One could use just about any object to form the basic shape or, as I did as a child, sculpt the area by hand to create a more organic form.
Because I thought it might be cool to have a little peg bottom we put a few indentations in using a pen tip. (Again, one could use any object or fingers to do something like this and create as many impressions as one found pleasing.)
After our mold was ready, we began preparation of the wax. Of course, one can recycle old candles for this step of the process or, as we did, use a block of beeswax. I don't know if it was necessary to grate the block into smaller shavings but it certainly cuts down on the melting time.
To figure out how much wax we'd need, we poured water in the vase we used to make the mold and then got an approximate volume by pouring that water into a measuring cup. This was about a 4 ounce candle.
I placed about double that amount of shavings into a double boiler (because the shavings dissolve into an smaller volume) and heated the wax until it had melted.
(Safety note: Beeswax has a melting point of about 145° F. It can ignite if heated past this point, so don't put it in the microwave as temperatures there can be unpredictable. Remove it from the heat source once it has dissolved.)
I had wick and wick button ready to go and dipped them into the melted wax and then into cold water. Then I used my fingers to straighten the string. If the wick is still wiggly, this process can be repeated until some stiffness is established.
This step can be skipped and the wick button isn't completely necessary. I just find that creating some stability in the wick makes for an easier time in the following steps.
We then placed the wick in the center of our mold and attached it with tape to a ruler (any stiff object that spans the container would do) to hold it in place.
We carefully and slowly poured in our wax. (If the container in which you're heating wax does not have a spout, I would recommend ladling the hot wax, rather than pouring it, into the mold. On another project, we made a huge waxy mess that ran across the top of the sand and down the insides of the bowl when we tried to pour it from a regular un-spouted pot.)
(
To save excessive cleaning of the melting vessel, wipe it clean with paper towels immediately after emptying it of its contents.)
That's pretty much it until the candle solidifies. This tiny one took less than an hour. Naiya was thrilled to pull it out of the mold and even used her own scissors to trim the wick (leaving 1/4" - 1/2" sticking out).
We'll use this as our story-time candle and hope to find some tales of sand and sea to accompany our beachy creation.