This idea comes from our friend Anusha Rajeswaran of Fish and Bull. This candle has one star ingredient: citronella essential oil. It's a summer staple for keeping pesky mosquitoes away. We use microwaveable soy wax since it's an easier and faster way to melt wax without a double boiler. Follow package instructions when melting to avoid overheating, which poses a fire hazard.
Cut a piece of wick that measures the height of your cup, plus a few inches. (For example, the height of our cup was 2 1/2 inches, so we cut our wick at 4 1/2 inches long.) Insert the wick into a wick clip and using pliers, pinch the wick clip to secure the wick; set aside.
Fill a microwave safe bowl with soy wax flakes. Follow the package instructions: Melt wax for 30 seconds to 1 minute depending on wattage. Check wax; if the wax looks like melted butter with some flakes, it's ready. If not, continue melting it at 30 second intervals. Do not leave the microwave unattended. Stir the melted wax with a stir stick until it has a smooth, pudding-like consistency.
Dip two thirds of the wick into melted wax; set aside to dry. Add two drops of yellow dye to wax. Add citronella oil, following a ratio of 3 drops of oil total for each cup of wax. Stir until combined; set the wax aside. (Note: Don't worry, the melted wax will stay in liquid form for several minutes before hardening.)
To attach the wick clip to the candle cup, use the stir stick to add one drop of melted wax first to the bottom of the cup and gently press the wick clip on top to adhere it. Use a clean craft stick to rest the wick against and keep it standing up. Now pour the melted wax into the candle cup and gently shake the cup to make sure the wax settles evenly; set aside to dry completely about 4 hours.
If you move it before it properly sets, the candle will get lumpy. Once the wax has dried, trim the wick to 1/2 inch above the candle and it's ready to use.