Fill your wax pitcher or aluminum can 3/4 of the way with wax flakes. Place the can in the center of a small saucepan and pour water in the saucepan until it reaches 2 inches up the sides of the can. Bring the water to a boil over medium heat and keep a watchful eye on the wax until it's completely melted.
Once the wax has melted, add your essential oils and stir to combine.
Pour the wax into one of the mold cavities and let it cool slightly.
When the wax has just begun to set, place dried flowers and herbs in the wax. Repeat until you've filled all the cavities.
When the wax has cooled completely, remove the sachets from your molds. Optional: Take a long metal nail and (carefully!) heat it for a couple seconds over an open flame being careful not to burn yourself. Use the nail to melt a small hole through the top of your wax bars (I found it best to start at the back and go through to the front). Thread a piece of string through the hole and tie.
Hang your sachets around the house or wherever you'd like to enjoy a clean, fresh scent.