Sandpaper cutter that the blade does not wear

Hello Friends！ I made a sandpaper cutter. Jig plan convenient for woodworking [Plan List] https://jsk-koubou.stores.jp/ By using a magnet guide, it is possible to cut the vertical and horizontal sides into 1/2, 1/3, 1/4, 1/6 and 1/8 sizes respectively. You can cut it to any size with the scale. How to make is also simple. There is no blade wear. The ruler is made of stainless steel but it is very cheap at 100 yen ($ 1). I got it at a nearby stationery store.