I did a quick remix of 3D Printy Print-in-Place Twisty Puzzle - Christmas Tree to have both simple and difficult versions of the Xmas case.
This is the latest version of each puzzle.
This is not the full print in place puzzle, you will need to print separately the internal part of the puzzle and the key.
I've remixed a gift box specifically for this great puzzle: https://www.printables.com/model/366558-gift-box-for-3d-printy-print-in-place-twisty-puzzl
I also remix a version of this print in place puzzle to be used as a topper in case you want to share twice the fun (I use the simple version of the puzzle as a topper to open the gift box and then use the difficult version of the puzzle with the Xmas tree):
https://www.printables.com/model/382617-gift-box-with-puzzle-topper-opener
The author remixed this model.