Recently I finished a small project to make a knife holder for the kitchen. It was made using one small block of wood, some screws and 8 magnets that came out of dead harddrives. The magnets were bought in Ithaca, New York from the Fingerlakes Re Use center ( 2255 N. Triphammer Road Ithaca,NY in the Triphammer Marketplace, phone 607-257-9699). Fingerlakes ReUse rebuilds and sells used computers ( much more other items as well ) and they sell harddrive magnets for 50 cents each (as of Sept. 2015 ). They have a pile of these magnets and it is worth picking through the pile to get some flat ones, looking for matching pairs and ones that will take a #6 screw for a project like this.
For the knife holder, I used a piece of oak flooring 3/4 inch thick, 10 inches long. It is best to use a piece of thick wood, because when you pull the knife off, there is a tendency to pull from the bottom handle out, which tips the knife towards the cabinet as the bottom magnet releases first. If the wood was thin the knife point would tip against the cabinet.
I cut the tongue and groove off the board ( trims it to 2-1/2 inches wide ) and then sanded it a bit on a belt sander to make the edges a bit rounded. Then using a drill press, I drilled out the holes to take #6 screws, 16 for the magnets (#6-5/8 machine screws), 2 (#6 – 1-1/2 wood screws ) with countersinks for the mount points. The whole process took about 20 minutes. For finishing I used a bit of linseed oil on it and then left it in the trunk of the car so a week while it was sunny and hot allowing the finish to be “baked” good and dry.
The magnets are rare earth magnets and are very strong. Therefore the piece of wood has to be screwed in good or it will probably pull off the cabinet when used. One caution with these magnets is that they will pinch your finger if you get it between them and another magnet or anything else ferrous. When I was cutting the wood I put one of the magnets down on the table saw. The steel on the table saw is so massive that the magnet was hard to get off, I had to use a screwdriver to pry the corner up, I could not lift it with my fingers!