this is my second holder and I thought I had taken photos how the inside looks but I think I never did.Essentially imagine a 12x12 paper and you score the paper so you have 9 sections scored. You would cut the 4 squares in the top /bottom corners out (this is just the visual) if you want to re-create this.. don't forget to add the height of your post-it note, so I added to my squares about 0.5. I used 2 12x12 of paper. If you create yourself a dummy first from old paper it's very easy to figure out.
These are the supplies I used:
Stamp: Winter Wonderland Collection "Show the Way Tilda"
Dies: Magnolia Doo Hickey Mistletoe, poinsettia
Memory Box snowflake die
Stickles: Star Dust, Diamond, Silver
Coloring: copics, white gel pen
Tools: Scor pal
Thank you and take care