Read all the given thoughts before you make everything and get annoyed if it didn't work <3

I was thinking. Why to buy a chocolate christmas calendar with bad chocolate, when you can print and fill one with all the good stuff there is. Of course it's not fun if you make it for yourself, but luckily I am married and can change calendars with my hubby! 

These aren't too big boxes because the idea is not to fill them with crap. You can fit nicely four of those whatever they are called in english -chocolates in wrappers and propably something small and nice if you want. The size is pretty easy to change, just scale it or if you make body longer so it takes longer boxes, you just resize boxes accordingly because they don't have inner dimensions, they don't suffer resizing. If you resize the whole thing, remember to see the numbers and gluing jig too. 

There are 24 numbers and one extra heart, because we have only 24 days to suffer, because we open gifts in 24th. So you know in the faraway lands. But I think you can use the heart to mark 25th. We use it as open-when-you-want bonus box.

Now to printing part! For some reason I could not get slicer agree with me to make holes to body part, so you have to put it there yourself. The holes are separate stl, just add both parts to slicer, merge and turn hole parts into negative parts. Holes! Boxes I printed vase mode with my MK3 with 0.8mm nozzle and that was just fine, but if you don't have large nozzle, you can just print them empty, 0% infill, 0 top layers and as many bottoms and perimeters as you wish. 

Note: test the size! There is no stopper to boxes, and if they are too small they don't stay put, if they're too big, they don't fit. I noticed that my different filaments gave different size boxes even with same given dimensions, some were way too small, some didn't fit, I have tweaked the size of the box back and forth, so test the size before you print 25 of them!

Gluing jig is there to get the numbers in the middle of the face. Sadly it does not help you to get it straight, you have to eyeball it.

This design is what I wanted, your needs might be different. Mine work, I hope yours does too if you print this <3