I got a wild hair to redo some of my bench planes with more consistent cambers. I have more than one of the smaller sizes and wanted one each to be different than dead-straight across. That's easy to do for a slight curve on the stones but either I don't have the patience or the technique for something more pronounced.
I have a Grizzly 10" wet grinder which is the poor-man's version of a Tormek that uses a horizontal bar to present the piece to the wheel. So ... I put a gentle curve on a piece of plywood with a plane and belt sander (maybe 1.5 mm), hogged a dado across it for a stop and glued in a scrap of ash about 3/4" square. I also put a strip of veneer down the center of the flat side of the ply to register the plane iron slot. Finally, I drilled a 3/8" hole in the center for a carriage bolt to hold the iron in place.
The jig is designed to rock slightly with the stop against the outside of the bar with the wheel spinning away from me. It's 3 1/2" wide to keep me from tipping it on edge and digging into a corner. I suppose it's possible to have different versions for different cambers but I did this more by feel. And it worked. I checked it against a square every so often and when it looked right, it was on to the stones. I did both a jack and my fore plane using the jig and am pleased with the results -- especially since it was free and only took 15 minutes to make.
I hope this helps somebody and good luck with your projects. Skip