A few years ago a friend bought me a set of three Lego bricks with magnets in them from when she went to Legoland. You can buy a different set online at the Lego store. I received a set of Magz as a gift and I noticed that the small magnets in the bar component of the toy looked like the right size to fit in the cylinder in the bottom of Lego bricks.
Any mention of this project must provide a link to www.zieak.com with credit to Ryan McFarland.
A basic set of Magz or rare earth neodymium magnets (5 mm diameter x 3 or 6 mm long)
A pair of diagonal pliers or a pocket knife or utility knife
Superglue (optional - the right size magnets will stay without it)
Step 1: Harvest the Magnets
It is quite easy to remove the magnets from the Magz. Just a squeeze with the cutters and then tapping the metal onto the magnet will remove them. Please note that this is a little wasteful - if you need to buy Magz or magnets for this project just buy the magnets. They should be fairly easy to find online. They must be 5mm diameter and you can stack two 3mm magnets (the size the Mags come with) or buy 6mm magnets for the best strength. I was given the Magz and used them for a little while before deciding that I would have more fun with the magnets. I used the steel balls on top of the soil in a potted plant to keep the cats from digging the dirt up. The plastic pieces were thrown out.
Step 2: Put the Magnets in the Lego Brick
You don't need to glue the magnets into the Lego brick. I did on a few and found that the magnets stay just fine without it. A little drop inside the round cylinder part of the Lego brick will guarantee they will stay in though. Once again, stacking two makes them nice and strong. By putting the magnet inside the cylinder the Lego can still be attached to other bricks (either ones with magnets or those without).
Step 3: Build Your Collection
I like the look of the classic bricks but any Lego piece that has the cylinder can be converted to a magnetic building block this way. Naturally the thin plate pieces would need a very thin magnet which would probably not hold very well unless you had many of them.
This project may seem familiar to some. I wrote up these magnetic Legos (Lego? What is the official plural of Lego?) on my personal website in January and Make Blog picked it up.