A flat-folding box cover with magnets near one edge of the side panels that align with magnets of the opposite polarity on flaps of the adjacent side panel to hold the box cover into position is provided. The flat-folding box cover includes a top panel with aperture and four side panels that when assembled fits over the top of a tissue or other box. Advantageously, the box cover may be kept in the flat state or folded into a box shape as needed.The box covers may be sold finished from a seller. In another case, consumers may select from a set of options provided by a seller for the box cover design. In another case, the consumer may supply the seller with custom artifacts such as photos or artwork which the seller would incorporate into the finished box cover. Kits may also be sold allowing the purchaser to customize the box cover themselves.