A while back I posted about a convenient way to store small tools in a water bottle cage - the product I wrote about is called the Cage Rocket. It's a plastic cannister that fits into a water bottle cage and unlike some tool bags that fit under your seat, you can remove the Cage Rocket and take it with you in one second.
Reader Edmond saw the post and contacted us with his own great solution - a plastic peanut butter jar. All text and pictures are credited to Edmund.
I started with a peanut butter jar that had been washed of label and peanut butter remnants.
Here is all of my stuff that I put in it laid out.
It took a bit of playing around, but it all fit inside. I then put the jar on the back of my bike, in a bottle cage. I now have a tool container that was free, is water proof, very light weight, and fits perfectly. The sock works as a hand rag and keeps rattles to a minimum. You could paint the inside of the jar to hide it's contents or just to make it pretty. I wasn't worried about it myself. I have used this system for well over a thousand miles without any problems at all.
A tennis ball can will fit in a bottle cage as well, will hold more, but won't seal as well. (I saw this idea on a forum somewhere, and did not come up with it myself. I wish I could credit the person who did come up with it, but I do not have that information.)