When they arrived, I cut 24 strips of construction paper to wrap around (to hide the contents). I used purple and the lighter blue, because those are the colors we have never used so we had a lot of them.

I just wrapped the construction paper around the bottom and taped the edge.
For the exercises, First Daughter will match the sound from one bottle with the matching sound, or the same for scents. So we have 12 bottles for each exercise, with two bottles holding the same scent or sound. The book suggests different colored lids, but I found it was cheaper to order all white lids and just used some extra stickers I had to indicate the groups.
I pulled things from the kitchen to fill our bottles.
Sound:
brown rice
cornmeal
lentils
oatmeal
popcorn
salt
It turns out the cornmeal and salt sound very similar, so I'll switch one of them out if we have too much trouble with it. Of course (and you may have noticed this), my nice bottles have a bit of space at the bottom uncovered by the construction paper (because of the shape of the bottles) so there's always the color to use as a guide.
Scent:
basil
caraway seed
cardamom seed
ground cloves
oregano
whole black peppercorn
If we have time, we're going to pull these out on the first day of homeschooling. So far, I've kept them a surprise and I hope the kids enjoy them.