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.
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.