I wanted to pack a small amount of chain lube to take with me on the upcoming trip. I've found that gear oil is a very good chain lubricant and I have been using it for years. The problem is that applying the oil to the chain is sometimes problematic. Spraying tends to get the oil everywhere and just pouring the oil to the chain is not very clever way either. The best way in my opinion is to use a brush on the inside of the chain. This way you can control the amount of oil that is applied. Oiling only the inside works as the centrifugal force will eventually push the oil on the outside too.
Having a can of oil & brush handy at home is no problem, but how to pack the two to take with you...? Having the oily brush rolling around in your bag is not an option and messing around with plastic zip lock bags or separate "brush containers" didn't feel sensible either. You could just drop the brush inside the oil can, but you would your hands messy every time you used it.
MY DIY SOLUTION.
1 ½ litre Castrol gear oil can with a pouring tip.
1 wooden or plastic paintbrush with a round handle
Eyeball the amount of brush you can fit in the can, cut the brush to length, insert the brush to the cap. Screw cap back on. Done.
Now you have an all-in-one brush-oil combo pack that will also keep your hands clean as you don't have to touch the actual brush.
I bet there is a commercial solution to this, but I just haven't found it yet.