Duo-Art accordion pneumatics are not terribly difficult to recover.
It is easier to use thin pneumatic cloth and also cheaper as good
pouch leather is expensive and you usually need to buy a full skin.
However leather is significantly better, is quieter and more supple.

Leather is more difficult because it does not hold its shape as well,
especially if you are a novice and do not have experience "dropping"
it on hot glue. Cloth is more forgiving since you can heat it with
a warm iron to reposition it but this can damage leather more easily.

I glue on strips of thin pneumatic cloth over the pouch leather to act
as stretch stoppers. The strips should be about 3/8" wide and glued at
the spots where the boards are. Position the strips where they will
not interfere with the adjusting screws and blocks and or stick on with
a tiny dot of flexible glue (PVC-E or Aileen's Tacky Glue work well)
in between the boards. Three strips is enough to keep the pneumatics
aligned but 4 to 6 strips also works.

The old instructions tell you to readjust the screws after a while to
compensate for stretching but if you use the fabric strips there will
be virtually no stretching. You can also compensate for any sloppiness
in applying the leather.

Spencer Chase