Here we have a nice Index Card tray and used-card divider to hold 6"x4" (152mmx102mm ) index cards.

Fresh notes on top of divider, un-used cards below or any combination that works for you.

Really cleans up my desk as I use Index cards for actionable notes that need to be followed up on. If you use index cards in a similar way, having a stash handy and organised makes a world of difference.

Print your own and see.

Happy printing.