The fireplace has a cut in the back of it to put in a piece of metal, so you can put magnets onto the stockings. Means it is scalable if the family adds an extra person to the fireplace.
There are two types of boxes for the main piece in the design too. You can do a box with a cutout in the front, or I have one that works with some little knobs I got off etsy (which is shown in the picture. When cutting the fronts you can choose which pieces to engrave/cut based on that. Also why there is two sets of numbers and door fronts!
There are quite a few similar to this on etsy already. Although I made this myself, started with the boxes.py to make a box with all the inside bits, then carved bits out and made a roof (also using boxes.py and the triangle boxes) Lots of editing and designing of fireplaces later.