What is more Christmassy than a photo of a christmas tree with christmas tree bokeh? Nothing..
I had a quick look on the net and found out some useful info. When creating a shape to make a custom bokeh, the size of the shape is determined by the focal length and aperture of the lens. I was using my Nikon 50mm f1.4. so the maximum size of the shape is 50 -:- 1.4 = 35mm. So I drew a circle the size of my lens (approx 75mm) and then drew a christmas tree shape inside it no bigger than 35mm.
A print out of my tree shape. If you want a copy of this I can upload a PDF..
I traced this onto black card, cut the shape out and stuck it onto a black 1cm strip to form an edge.
A shot of the christmas tree with no bokeh filter.
Same shot with the bokeh filter added..
A closer view..