| 摘要 |
A flexible cover is formed from a rectangular sheet of plastic film material and a continuous elastic or rubber band. The sheet has a predetermined amount of material cut from each corner. The sheet is placed onto a table between four posts that extend from the table. The sheet is positioned so that a post lines up with each corner of the sheet. A rubber band is stretched across the four posts into a similar shaped rectangle and rests just above side edges of the sheet. The side edges of the sheet are folded inward and over the stretched band and heat sealed directly to the sheet. The band is now sealed within a pocket formed along the sides of the sheet. Each corner of the stretched band is released from its post, allowing the band to relax and pull the formed pockets toward the center.
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