To begin, fold a fat quarter in half lengthwise, then fold in half again, with raw edges just inside the fold line. It should measure about 4 -1/2" wide by 21".
Begin at one end and fold the corner over at a 45-degree angle, aligning with the outer edge.
Fold the triangle up again, keeping sides aligned. If you've ever folded up a flag, it's done in the very same manner.
Repeat the steps.
Stack 3 triangles together to form a 5-pointed star, like the one I received from Joan in a recent exchange:
Now try folding your fat quarter at a 60-degree angle. Use a mark on your mat or ruler if you want to check the angle.
Fold to form a triangle and align with the edges. Repeat.
Tuck the ends inside the last flap.
Stack 2 equilateral triangles together to make a 6-pointed star, then add as many more as you'd like for a starry tower.
Stack 2 or more equilateral triangles inside each other...
add another rolled-up fat quarter for the trunk and you've got a little tree stack.