After looking at a few other options out there, I really didn't gel with any of them, so I decided to design my own. The font used for the cut out letter is VanBerger. The retaining clip is designed specifically to attach to a IKEA KALLAX, as that is pretty much the defacto vinyl storage solution.
Note that the included Fusion360 model uses the exceedingly helpful Parametric Text add-in, which you will need. The letter on each divider is set using that.
Typical print (0.20 quality w/15% infill) uses 7.2g of filament per divider.
The author marked this model as their own original creation.