For those who like to keep it small, keep in mind that this is a survival kit and you don't need to have stuff for every situation. If you want to KISS and small think about what you need for the basics of food, water, shelter, signalling, and fire; then carry them all on your person. This is what I carry:
Food:
- some food; snickers bar(s), whatever you like
- aluminum foil for something to cook in or drink from
Water:
- water purification straw or tablets
- 2x each, zip lock bags
Shelter:
- ORANGE space blanket for shelter- duct tape wrapped as described earlier
- 2x leaf size trash bags folded up; you can cut them open and tape with the duct tape into a tarp for a shelter, or use them as a sleeping bag, or any number of other purposes
Signalling:
- see the ORANGE space blanket
- my compass has a mirror on it
- aluminum foil from the FOOD list works too as does the flashlight from TOOLS
Fire:
- waterproof matches and firestarter; your choice for the firestarters
- magnesium match
Tools:
- sharp knife; I have a swiss army knife that is my mobile toolkit
- compass in my kit and at least one on my body
- map of where I am
- flashlight of some size
- first aid kit with sanitary napkins, big gauze pads, bandaids
This will all fit into the two zip lock bags mentioned under water and they will each fit nicely into a cargo pocket in your hunting pants. This way you have shelter for the night, food to keep up your spirits, and the tools to make it all work.
You will notice that I didn't mention butane lighters because they won't work as the temperature approaches freezing. The fumes burn, not the liquid, so if its so cold you can't get fumes then you can't get flame either.