This was in a Pottery Barn catalog a few years ago. Not sure now if it was for sale or just a prop, but I vowed to make one. You gotta love those scrapbooking doodads, especially the numbers and letters. I combined them with address numbers, game pieces and refrigerator magnets for this project.
white spray paint
white mat board
Buy a box with 24 or 25 openings. If this is not possible there are several options:
1) Combine several boxes with fewer openings to add up to the required number. If you end up with more than 25 openings, fill the extras with words such as "Merry Christmas", "Noel" etc.
2) Partition a plain box or tray into 25 openings using thin wooden slats or foam core board.
Paint the box white and prepare 25 numbers. Glue larger, two digit numbers to white mat board.
Fill the empty box with candy, replacing the candy with a number each day until Christmas. A neat reverse of the open-the door-take-out-the-candy type advent calendars you can buy and a terrifically colorful graphic statement.