This simple but effective tool rack can be made from a piece of wood and some of those neodynium magnets you have been salvaging from hard drives.
Take a strip of wood about 1 cm thick and use a router or chisels to create a cavity where the magnets can be hidden. Use epoxy to glue the magnets in place. Note that the magnets shown here are the wrong way up; they should be mounted with the magnetic strip facing down.
Pre-drill two screw holes (shown here in red) so you can mount the strip to the wall. Sand it down and chamfer the edges to make it look nice. Now screw it to the wall and hang up your files and chisels.
TIP: removing the back plate from the magnets seems to reduce the magnetic field so you better leave them as is.