To start, I cut two strips of fleece 3" wide, and two 3" strips of this adorable fabric. I bought this fabric a long time ago, not really sure what I would do with it. Now, it seems to scream "essential oils!" Then I cut an equal length of medium weight interfacing at 2". I really wanted to cut it at 2 1/2" (so I could catch it on both long seams), but I didn't have enough to do that, so I'll have to make do at 2", since I don't want to wait until I make it to the fabric store to buy more.
After pressing, I hand stitched the open end shut, then hand stitched the two ends together to make a big loop. I forgot to take a picture at this point, oops.
I fiddled around and figured out that a 4 inch opening would hold the bottles snug, so I sewed lines every two inches down the entire length of the folded loop. I ended up with nine "pockets" on one loop, and nine and a half (perfect for a 10 mL roller bottle!) on the other.