Add the dandelion-infused oil and emulsifying wax to a heatproof jar or upcycled tin can.
In spite of its name, magnesium oil is actually water based, so measure it out with the water and aloe and place in a half-pint (250-ml) canning jar.
Place both containers into a saucepan containing 1 to 2 inches (2.5 to 5 cm) of water, then set the pan over a medium-low burner. Keep both containers in the pan for around 10 minutes. This gives time for the wax to fully melt and the water, aloe and magnesium oil combination to reach a nearly matching temperature of around 150°F (66°C). Remove from heat.
Carefully pour the hot contents of the two containers into a heatproof mixing bowl or measuring pitcher. As they’re poured together, the separate mixtures will begin to emulsify upon contact and turn a milky white color.
Using a fork or small whisk, stir the lotion briskly for 30 seconds, then set it aside to cool down for around 5 minutes. To speed up the cooling process, place your mixing container down into a bowl partially filled with ice cubes and water. Stir occasionally, for around 30 seconds at a time, as the lotion cools and thickens. Stir in the lavender essential oil, if using.
If you’re adding a natural preservative, check the temperature and see if it’s the proper time to do so. Recommended temperature will vary according to type, but preservatives are usually added when the lotion is cooling.
Pour or spoon the lotion into a bottle or jar. The lotion will continue to thicken as it sets up. Keep tops and lids off until it’s completely cool, to prevent condensation from building up on the lid.
If you didn’t add a preservative, store your cream in the refrigerator and use within 2 weeks. Apply to legs, feet and back at night, or as needed when leg cramps strike.