I got tired of just wraping sandpaper around a block of wood. Sometimes I would sand away part of my little finger. Ouch! And it just didn’t fit my hand right. So I designed a quarter sheet sanding block. A machine screw provides the clamping force to hold the two pieces together. The bottom section starts with a good piece of plywood with a lot of plys for dimensional stability. I counterbored the plywood and then drilled a through hole. After installing the threaded insert, I glued on a piece of hardwood for the face that would backup the sandpaper. I also installed two dowels of different sizes to register the top to the bottom. The top is just a piece of 2×4 drilled to accept the dowels and the machine screw. I experimented with a wood rasp to make the top fit the palm of my hand. I also made a “Jumbo” model by laminating another piece of wood onto the top. Both work great and they sure beat a regular block of wood. I keep one handy to knock off any rough edges if I use a hand saw to cut a board to length. You can make several and keep different size grit sanding blocks at your fingertips.