I would make a muslin bag with a draw string and stamp a pretty heart or herbs or initial on the front and then fill it with the recipe below. They would hang on the bathtub faucet and I would let the water run through and over them while the tub was filling with the scent of lavender or whichever scent I had in the bag. Before I got out of the tub I used the bag as "scrubby" on elbows and heels.
I usually made the bags about 3" x 4" and filled it with:
Oats (not the quick kind)
Drop or two of Lavender essential oil
These ingredients are at most grocery stores. You can find the oil and lavender flowers at most health food stores. I hope you enjoy your bath bag!