I was looking for a way to sand the edge of a piece of wood without adding an unwanted chamfer.  There seems to an endless supply of 3D-printable sanding blocks, but none that I found with a right-angle guide on them.  I came across a wood-based one (https://www.woodmagazine.com/woodworking-how-to/shop-tips/right-angle-sanding-block-keeps-edges-square) that I was temped to make.  But seeing as how I have a 3d printer, I decided to try to come up with my own.

This is an all new design, but it is heavily inspired by the wood version mentioned above as well as by [https://www.printables.com/model/22236-customized-sanding-sticks-with-labels](https://www.printables.com/model/22236-customized-sanding-sticks-with-labels) and other similar models out there.

This is sized so that a 9" (~23mm) strip from a sheet of standard 9x11 inch sandpaper will fit it.

Print Instructions

You'll need to print the sanderblock, holder, and 2 copies of the screw.  You can also optionally print the cutting guide which is the size of sandpaper you'll need.

I used 0.2mm layer height, 20% infill (I am sure 15% would have be fine), and printed it with PLA.

For holder.stl and cuttingguide.stl, print in given orientation.
For screw.stl, flip so screw head is on the bottom.
For sanderblock.stl, flip over so that the narrower part is vertical and the thicker part is toward the bed.  You will need supports under the gap.

It might take a little work to initially get the screws screwed into the holes.  Be sure no supports are left inside the holes.

Parametric

The FreeCAD model is included and is parametric so you can alter the size to meet your needs.  Load the .FCStd file in FreeCAD and double-click the Spreadsheet in the list of objects on the left.