I saw the idea used as a bobby pin, and decided it would also make a good card.
The tree focal point is made entirely of ribbon - you need about half a metre. Cut two 8cm lengths, two 7cm lengths, two 6cm lengths and a different colour piece for the trunk. Fold each piece in half and glue the ends together. Glue your ribbon "trunk" in position and the glue the two longest loops at right angles to each other at the top of the trunk. Continue upwards using shorter loops each time. Finish off with a star or similar at the top of the tree - a button is my favourite. Easy peasy and super quick!!
Of course you don't just have to use ribbon. Strips of torn fabric, crepe paper, felt, off-cuts from mixed media paper-cloth - they will all work fine. You could machine stitch them in place through the centre if you prefer that to gluing. I did one using sheer ribbon and an acetate card front. I attached the ribbons with brads, but it didn't photograph very well, so I haven't included it.
This one uses scraps of patterned paper. The loops would get flattened if sent through the regular post, but it is OK if you are delivering by hand.
Let me know if you think up any good variations.