I went to polish my plane blades tonight, front and back. Thing is, hanging on to the plane blade is awkward, slows you down, and usually gives you a swarf-fill cut from time to time. I wanted a handle for the blade to simplify matters.
I have a Veritas Flush Plane I use mostly for dealing with glue squeeze-out. The handle has a lip on the back to catch the blade and a very powerful rare earth magnet that holds the blade in place. This makes removal trivial for sharpening. I took the blade out and stuck my regular plane blade in. Voilà! A handle for lapping the front or back of the blade.
The blades don't all fit perfectly centered or anything, but the magnet more than holds the iron in place while you swirl it around.
It's interesting to see how the swarf gathers close to the magnet; doesn't affect lapping, just when you lift it :)
You could make the same thing if you aren't interested in the flush plane. A block of wood with some really strong rare earth magnets epoxied in place and a screw left proud will work. The screw, in this case, takes the place of the small cylinder you see in the hole; it is used to register the flush plane's blade correctly.
Great idea, thanks.