Just in the off chance you still need an advent calendar this is fun and easy. Gavin saved me from my own elaborate calendar creation this year and steered the process in this direction.
Turns out that two egg cartons make just the right number of little cells to nestle a daily treat inside. The boys each painted two cardboard style egg cartons and then "glittered" them with the bits of crushed up painted easter egg shells we saved (it's really hard to part with these things, you know?)
That night, while our excited littles were dreaming, Travis and I busied ourselves with the finishing touches, wrapping a little gluten-free treat in bits of colored tissue paper, stuffed them into each of twenty-four little spaces, secured each carton it to a thick paper backing with hot glue, wrote numberes 1-24 on the cells. A treat (or two) per day until Christmas!
I promise you, it's not too late to get an Advent calendar together for those eager little ones - hey all they need to do is double up on the treats for a few days and voila! you're all caught up.