Traditionally, the Advent Calendar ends on the 24th. You get plenty of other presents on Christmas Day. So this final box is unnumbered.
The star is in two pieces, meant to be printed in contrasting colors for a starburst effect. I used yellow and transparent ABS. The parts of the star fir together with a couple of pins. Depending on your printer, the fit may be tight or loose. If necessary you can glue the parts together.