This barely warrants pictures, but I'll upload them anyway.
I just put some tools (3 tire levers) and spare parts (valve caps, a schrader valve core, zip ties...) in my long 26.0 diameter bicycle seatpost. I then put a spare handlebar cap into the end to keep the stuff from falling into my frame.
It is a very simple idea, but I think it has potential, maybe hiding other useful things in the tubes of a bicycle.
Step 1: Laying Out the Stuff
One needs to figure out an arangement of the parts and tools that will fit in the seatpost. The levers only fit side by side with their hooks facing opposite directions.
Step 2: Put the Stuff in the Post
put the levers, small parts and zip ties into the hole.
Step 3: Cap It Up
Put end cap into post, and reinstall seatpost.
No one is the wiser but you...