O2 Bottle Space

I am curious how to best utilize my unused oxygen cylinder receptacle
space. Since I fly in an area where we rarely get above 5,000 feet, I
have available for use this long empty slot. It would be great to be
able to use it to store items that I might want to get to during
flight. The trick would be having some way to pull the items out to
access them in flight and then be able to put them back for access at
a later time.

I was thinking of a container with a rope attached at one end to pull
it most of the way out and then push it back when done. However, I
can't think of any durable, lightweight containers of the appropriate
dimensions.

Any ideas or suggestions for making use of this potential storage
space?

Thanks!

WD