Most of the sanding block models on line are larger than I would like, but I liked the basic design of Christoph Wienands' on thingiverse, so I used it as a inspiration and completely remodeled using OnShape to suit my fancy. I know it doesn't use a normal fraction of sheet of sand paper, but it should be small enough to get 4 maybe 5 pieces out of one standard 9x11 3M sheet.