I thought it would be useful to have a sanding stick so I modeled one in Fusion360. Once it's printed, tightly tape the sandpaper around the stick. It helps to use the back of a hobby knife to score the back side of the sand paper lightly to give sharp creases. When you've used up a portion of the sandpaper, you can tear it off and use what's underneath.
The author hasn't provided the model origin yet.