I thought there was a tutorial already here so I did not bother taking any before shots.
http://badgerandblade.com/vb/showthread.php/108797-DIY-Magnetic-Straight-Razor-Sanding-Jig
The base is Poplar, the two rare earth magnets came from an old hard drive, and the backstop is ebony. I carved out holes for the magnets in the base plate, then set the magnets in two part epoxy and let it cure. Then I sanded flat the surface and glued down an aluminum hobby sheet. Set the back stop with small screws. Then using a file, I smoothed the edges of the aluminum. Works great, but the magnets are really strong.
http://badgerandblade.com/vb/showthread.php/108797-DIY-Magnetic-Straight-Razor-Sanding-Jig
The base is Poplar, the two rare earth magnets came from an old hard drive, and the backstop is ebony. I carved out holes for the magnets in the base plate, then set the magnets in two part epoxy and let it cure. Then I sanded flat the surface and glued down an aluminum hobby sheet. Set the back stop with small screws. Then using a file, I smoothed the edges of the aluminum. Works great, but the magnets are really strong.