build a fire without using matches (10 points): this one was the hardest for me, and took months of nearly daily practice. someone said to me "did you use a flint?" they were impressed when i said i'd chosen hand lens.
make a camp cooking utensil using found natural materials (5): i made a roasting fork. sometimes simple tools are the best.
use stone tools or do flintknapping, the technique of shaping flint to make useful items (10): i actually studied flintknapping in college and while you can't always get real flint, you can usually find shales that will flake off enough for you to use as knives and hole punches. when i was making my little boat for this challenge, i used some flaky shales for my cutting edges and hole punches. shales are only temporarily useful as tools; they make sharp edges, but they're soft and so don't last long. not everybody lives near a good flint deposit, though, and you make do with what you have. early people who lived near good flint deposits could use flint in valuable trade.