Click on the image source link for instructions on making this advent calendar as a memory box. I just love this!
This is not just an advent calendar idea. This could be used to decorate any room and to put little keepsakes or even love notes inside.
The boxes are made with with cardstock and glued together. I can see this being individualized for any size memory box that you might find.
I found another source with instructions for making origami boxes, so there are a lot of options for making the boxes.