UPDATE - Due to user feedback, I have modified the front opening so that you can access all the way to the base. This should allow for access to 100% of your Post-Its.
This is a simple tray to hold a standard pad of 3"x3" Post-It notes. I highly recommend using this on a magnetic base tray using the 6mm x 2mm round magnets recommended by Zach on his heavy base model - https://thangs.com/designer/ZackFreedman/3d-model/Gridfinity%2520Baseplates-60925
The author marked this model as their own original creation.