Disc-bound Notebook Systems are very useful and customize-able. There are several different brands in the market - Circa by Levenger, Arc by Staples, Office by Martha Stewart, TUL by Office Depot, IQ 360 by Walmart, etc. and they seem to be inter-changeable when it comes to their accessories.

I am using the Arc System from Staples to keep myself organized. I have different sections for different topics. Some times I need to mark a where I am within each section.

I printed and use tinaw's Parametric todo list stencil (https://www.thingiverse.com/thing:1610575) with holes for disc-bound notebooks. Modifying her OpenSCAD source file, I made my Disc-Bound Page Marker.

If you print, go with a 0.1mm layer height for increased strength - should give you 5 layers.

Can print in different colors too.

Please share your picts of the different colors you choose to print and use.