I found this on facebook:
Menthol Shower Pucks
1 Cup baking soda
1/2 cornstarch
1/3-1/2 cup water
2-3 Tablespoons mentholated rub
Heat water enough to melt the rub in, add dry ingredients and mix to a thick paste.
Line muffin tins with paper baking cups. Fills each about half-full with mix.
Let dry overnight.
When pucks are hard, remove from cups and store in air tight container.
Toss a couple in the tub when you shower and it will ease your congestion.
:o])
Sounds nice!