The most economized way to do it would be from scratch. Find a piece of foam the density that you want, cut out a couple doughnut shapes and adjust their height to be suitable for the density of the foam, then buy at least a couple square feet of nice cloth from a fabric store and cover them. Don't mean to be too personal but if your mother is around and into sewing she might have all the materials needed.
Glue the cloth onto the back of the foam, then glue it to the cans. If you can salvage the snap-in plastic plate piece from the old earpad then you can glue that onto the back of your new pads and have them be removable like the originals were.
You could get even fancier and use pillow wadding with glove leather cut & sewn over it to make a doughnut, or still cloth instead of leather... it's just making a little pillow with a hole in the middle.
FWIW, one thing that I noticed made mine degrade badly was exposure to UV/sunlight. I had a pair in the back of my car, half covered by a jacket. The half that was exposed to the sun had the cushion totally disintegrate into a little pile of fuzzy stuff in a cloth bag.
Edited by mono - 1/27/12 at 1:20pm
