In Germany all children will get their special "before-Xams" calenders tomorrow. The advent calendars usually have 24 little doors to open - when I was small there was a little surprise picture behind it. When I was 5 I got my first 3-D calendar - I'll show it in a few days, as soon as I find the time to dig it our of my treasure box. At the same day my cousins got the first chocolate calendars with a piece of chocolate behind each little door.
When our children were small I used to get little things like Lego blocks or pieces of a puzzle to put into little boxes. One year I folded up 96 half boxes to make 2 x 24 boxes myself to hang onto a star for both girls. Some of the little boxes got used for other things over the years, but one set is still complete and will travel to our oldest daughter tomorrow. I don't know, if she can hang something, so she'll get just the boxes to put on her window sill.
Charlotte's advent calendar.Johanna's advent calendar
My husband's advent calendar.