Today I am going to teach you how to make a whistle from a bottle cap. This could be very helpful if you were to get lost because whistling takes a lot less effort than shouting. You can also do this on an acorn and if you're really good on a bottle!
Step 1: Formation
For the formation you need to hold the cap in your hands and use your thumbs to make a "V". Do not put your thumbs flat on the cap. Make sure you make a small gap instead of a large gap or the air won't flow correctly.
Step 2: Blowing Technique
For the blowing part you need to have you're bottom lip on the bony part of you're thumb. Blow a steady stream on the lip of the cap. You may have to repeat this step a few times before you get the correct noise.
Step 3: Keep Experimenting!
By now you should've made a noise by now. It only took me a few minutes before I learned this skill and it has helped me a good bit. If you are a beginner I would start with something easy to grasp and with more depth in the cap like the coke cap. The coke cap makes a course noise but can reach pretty high. The clear water bottle cap is ear piercing and the bottle cap is the hardest due to the curvy lip. Remember that the smaller your gap is the higher the noise and try with multiple different objects.