Sentry gun safes has an arrangement like what you describe on the rear of their doors.. it's elastic (bungee) cord criss crossed in an X pattern. I bought a bunch of zippered nylon storage cases/pouches and stuck them under the cord.

Ona bare bones safe, I used add-on auto map pockets with an elastic band on the top opening that hold them closed. I glued on magnetic tape strips on the back of the pouch to stick onto the inside metal door panel. I could have use sheet metal screws but didn't want to drill the panel, plus with the mag tape they were re-positionable.

Take a walk through an auto parts store or Wallyworld and take a look in the auto accessories section... lots of storage gizmo's there that can be adapted for use.

__________________
Conrad
SWCA #1830 SWHF #222