Abstract: The present invention relates to an expandable packing device applied to a paper holder, a portfolio, a diary, a PP file or the like. The expandable packing device includes a first sheet, a second sheet kept extended from a first edge of the first sheet, a first expandable part disposed between the first sheet and second sheet, a third sheet kept extended from a second edge of the first sheet adjacent to the first edge, a second expandable part disposed between the first sheet and the third sheet, wherein the second sheet and the third sheet are kept spaced with the first sheet and secured with each other, so as to form an expandable holding space with the first sheet.

Abstract: A medium for decoration includes a cover sheet having a cover color and a plurality of holes thereon so as to form a certain pattern; at least one replaceable colored sheet which is replaceably placed behind the cover sheet so that the colored sheet is exposed to the cover sheet through the plurality of holes. Each of the plurality of holes has a particular shape and the plurality of holes have a particular distribution so as to form the certain pattern. When one colored sheet is replaced by another one, a color exposed to the cover sheet through the plurality of holes is accordingly changed so as to change the color of the certain pattern. A method for decoration is also provided.