I've been thinking about making this since last Christmas when my future daughter-in-law asked if I could make them one. After scouring through Pinterest I found this one with pretty clear instructions: floatingworld.typepad.com/floating_world_views/2013/11/little-forest-advent-calendar.html
I am happy with the finished product, only wish I had done all the numbers in white. The red check doesn't stand out nearly as clearly as I thought.
Gifted and ready for it's first Christmas.