The Dremel EZ Lock Mandrel (lower right in first photo) makes interchanging tools on Dremel motor tools, or any other tools that can accept a 1/8" shaft, such as a Foredom, particularly easy. Push down, twist and the sanding disk, buffing wheel or other tool fitted with the female part (see example next to mandrel) that mates to the mandrel locks in place instantly; no messing with collet chucks, keyless chucks, or chuck keys.
The buffing wheel shown in the photo does a superb job removing flash rust from tools and leaving a very finely brushed finish so I use a lot of them. However they wear out fast and it really pains my stingy nature to discard that EZ Lock fitting when they do. I decided to try making an EZ Lock sanding disk from this one.
I rough cut a disk from thin plywood and fitted an M2 screw in the middle to act as a guide when the disk is glued to the female fitting. I chose to use JB Weld for the glue since the available area on the fitting is small so I want a tenacious glue. The part of the screw that goes into the fitting for centering was liberally smeared with grease so the glue wouldn't weld it in place.
When the glue dried, the plywood disk was attached to the mandrel and spun against a sanding block to remove all traces of my errant sawing. Then it was traced onto a piece of self-adhesive sandpaper disk as used on larger disk sanders. This was cut out and stuck to the plywood yielding a new, somewhat larger than Dremel size, easily-interchanged sanding device with replaceable sandpaper.
Next time you're about to discard one of those fittings think about what unique, specialized attachment you could make to add to your Dremel arsenal.