Years ago I made as similar one from pine, but smaller and glued a Popsicle stick on one side to hold the edge.
It was still too easy to cut your self.
So I switched to a 3X12 in piece of 4mm foam. I too use WD40 and the whole strip can be cleaned in the sink with simple green or any spray degreaser. When it gets to funky toss it and cut another strip. A 9X12 in pad of 4mm foam is around a dollar.
Attachment 167788Attachment 167789
Pressing down on the blade while hand sanding buries the blade in the foam and you can sand or polish right to the edge without any danger of cutting yourself. It also prevents scratching the blade once polished, use either a clean piece of foam or lay a paper towel over a dirty pad.