I happen to live near the beach so I collected some sand and took a funnel and layered about an inch or so in the bottom of the bottle.
Then I placed the gems and the shells in on top of the sand and dropped in the dried sea grass/flowers for some height. Next, I carefully poured in some clear tiki-torch fluid. I did not buy a bottle wick at a craft store, choosing to make my own using wicking and a cabinet knob. I removed the screw from the knob, stuck the wicking through the knob hole and fed it down into the bottle. You can use chopsticks to move things around either before adding the liquid fuel or after. The last step was to wind some twine around the neck of the bottle. You can tie it off or glue gun the twine to finish it.
This is a great way to re-purpose those cool bottles usually thrown out or saved for some other purpose (I keep dish detergent in one by my sink too!). It’s an easy project that can be tailored to your own decorating style.