I carry the Condor molle pal side kick. I just throw it in whatever purse I have that day and keep it in my car the rest of the time. It contains my basics.
The reason I use this is because what usually happens is that I end up carrying just my pen and phone in my hand and leave everything behind on accident while searching, so I needed something much MUCH smaller, lighter, and less packed. I switched to the molle pal because it is basically a tactical fanny pack that hooks to belts or can simply slip onto my forearm, and... it looks cool.
I tried a fanny pack, but it was too jumbled, and I always forgot to grab it.
For full geocaching days I throw it in a t-shirt fabric drawstring bag which I prefer because it is stretchy, stays in place when crawling, climbing, bending, etc, and most importantly, collapses to the size of a fist when not in use. That contains a lot of random gear for long days.
