So I recently bought a couple new kitchen knives and wanted to get a magnetic bar to hold them. I couldn't find one that fit my space and looked nice, so I built one.
wood of your choice
Neodymium Magnets, 1 per knife/tool you want to fit
I used http://www.magnet4sale.com/Neodymium-Magnets-N42-0.75-X0.25-X0.5-NdFeB-Rare-Earth-Magnets.html
Router or Dremel with router attachment (The Dremel is OK but not ideal, the plunge router attachment is difficult to fine tune adjustments and because it's plastic it's just not repeatable with a high level of accuracy, a real router on a table would have made this much easier and cleaner.
Just simply rout a 1/4" wide (width of magnet) slot into the back of the wood, keep routing until the wood is only about 1mm thick, superglue the magnets in place. The magnets I linked will hold a big Chef's knife very sturdy with 1mm distance between the magnet and knife. Be sure to check the polarity on the magnets you buy or get cubes so you know they will work in the direction you need.
Then mount it on the wall, I screwed it into a cabinet from the back side so it's a very clean look on the front.
Here's the pictures.
The wood was actually a Trivet that my wife found at Homegoods, its made of Olivewood and gives a nice rustic look. I had planned on just using some Poplar with decent grain.