Hey it's not so hard. Well, I don't make inkjet masks for 35mm but I do make silver masks. Doesn't take longer than making a 4x5 mask. I don't use them for sharpness enhancement though, just to help burn/dodge when it would be impossible to do it by hand.
Originally Posted by Nicholas Lindan
To old and feeble: google Alan Ross Selective Masking. He begins with explanations on pencil shading masks and then moves on to how to make inkjet masks with colors for contrast adjustment - exactly the thing you are describing.
He uses layered pencil shading masks and inkjet masks to help him churn out all the reproduction prints of Ansel Adams's negatives for the Ansel Adams Gallery.