This is a very simple A6 Christmas card but it's so effective!  This one's straightforward enough to be done multiple times as a general card for friends and family.

For this one print:-

The Christmas Front Door sheet onto quality CREAM card
The green holly backing paper onto quality white paper

To make the card, cover the front of a cream A6 card blank with the holly backing paper using double-sided tape.

Using a craft knife and ruler, cut out one of the front doors that has a wreath, cutting off the door-frame.  Also cut out one of the large letters/cards.

Mount the front door onto a larger piece of gold metallic card with double-sided tape and trim round with a craft knife and ruler to leave a small border.  Stick to the card blank with further double-sided tape.

Cut out a 15 x 5mm piece of gold metallic card to make a new letterbox and build up each end with an additional layer of scrap card/double-sided tape just to raise it up slightly.

Stick the letter/Christmas card to the door with double-sided tape and add the letterbox over it so that it looks like the card is hanging out of it.