I use an old CD bookcase for flavors too !
Cardboard trays to hold flavors in groups : Bakery / Fruits / Strawberries / Vanillas / Creams, etc…
Handles odd sized bottles well and has room for 1 more shelf.
Pull out the trays, mix, and put back when done.
It’s pretty good, but still have to dig around in each section to find the flavor I want.