Many have you have tackled this challenge in such wonderful ways- your creativity and talents are really inspirational! 
I also had to put my creativity to the test to draw on all the elements- this one is indeed a challenge! 
The first part of my challenge was a meditation on the elements and defining them clearly in my practice 
. After pondering deeply, I decided:
In my personal practice, I choose to honor 4 core elements (fire, water, air, and earth).
I explored my beliefs and determined that- for me- the combination of these basic elements creates the power of spirit/life energy
With this defined in my practice, I decided to put together a bath ritual that draws on the 4 elements…
Elemental Bath Blend for Increasing Spiritual Power and Balance
The central element here is Water (for a bath ritual):
Sea salt
Cornflower petals
Blue Butterfly flowers
Aquamarine crystal
The other elements are supporting the central element and appear in a triangle- helping to provide support and balance:
Fire:
Carnelian stone
Pink candle
Earth:
Bloodstone crystal
Fern clipping
Air:
Citrine stone
Bird feather
The ritual is set-up and blessed with a visualization- activating the cornflower and properties of each item on the altar in turn 
.
Then the set-up remained in place until the candle burned out- signifying that the bath blend is fully charged and ready for use
Finally, the triangle remained close to the tub while the charge bath blend was added to the water- it made for a very soothing and relaxing soak! 
Incorporating the elements is a challenge with many rewards- thanks again to everyone for sharing their wonderful creativity as they explore the elements!
Blessed be 