This pop up card, is window (or flat box) style, a mechanism well used by Tracy Chong and Willem Boning.
The scherenschnitte tree pattern is from paper cutters.
It looked a little Christmas-in-July to me, so I went with it. For the outside I used striped paper I had left over from last year's cards.
Click to download new file set! SVG, PDF, DXF, Silhouette Studio (3 and legacy).
Updated 2015: I finally dusted this file off and took the time to clean up and connect all the little lines segments. This one should cut much, much better than the old file.